Hub is C8 Pro on the 2.4.3.171 platform.
ZWave is switched again to the ZWaveJS just to see if any improvenets was added. And again, many random sizable delays started to pop up left and right but this is different story (already mentioned).
For a lo...ng time I did not have to add/remove devices. Today I desided to exclude few unused ZWave Sensors (they still was functional but was not used in any automations). The ZWave Exclussion process was started but near instantly was abruptly interrupted. Instead of 30 sec the longest ZWave Exlussion timeout was oround 20 sec (usually near zero). I tried this thousands times and eventually the devices were excluded but without any related message.
The hub reboot did not change this picture.
So, it looks like the ZWave Exclussion is broken with the ZWaveJS.
I have no idea what behavior will be with the ZIP.
I've excluded multiple devices w/Z-WaveJS and for me it works much more reliably and consistently than ZipGateway exclusion ever did. I can't remember ever having an exclusion fail using Z-WaveJS.
What I have seen w/Z-WaveJS is the Z-Wave exclusion process seems to stop on it's own earlier than expected as you note w/out any messaging. However, in those cases on my hub (C8-Pro) the devices were actually exlcuded, but the normal "z-wave device X excluded" messaging did not appear.
I assume from your post that you're saying that the messaging did not appear and the device was not excluded?
Can confirm. I have excluded over 40 devices with ZWaveJS, and this is my observation as well.
Thanks...and you have also found that the devices have actually been excluded, even though the exlusion messaging was missing?
In my case the ZWave Exclusion process was stoping abruptly in a 1-2 seconds range. But after many tries (around 20+) the device(s) was excluded but yes, without any messages. To my EE eyes this is not a right way to exclude a devices. This is definitely a problem which MUST be addressed and fixed.
Have you tried resetting the zwave radio using a powercycle? My exclusions work on the first try, albeit without a message.
Yes, I tried to reboot hub with and without power down.
This did not change anything (unfortunately).
Funny, but the ZWave Exclusion process usually stopped before I was able to release a mouse button.
I've seen that super short exclusion behavior before, but I just now excluded 2 devices (1 LR, 1 mesh), and both went as advertised - normal window given, and successful full exclusion messages for both. I'm currently on ZIP.
Surprisingly in my case ZWave Mesh works much better with ZIP. But periodically I am trying to switch to ZWaveJS (just did it again) because ZIP support is basically stopped.
JS needs a few days to settle. In large networks may take 3-5 days. I would expect things to be rocky in the first week. If you just switched, let it be for a week, then try again.
Switch to the ZWaveJS was done more than a week ago.
I know, it takes time.
Good to know, just make sure you share the full picture of what you see on your end, so others can help. You said "just did it again" instead of sharing when you actually switched. Also, you didn't share what devices you are working with, or if you see any errors in the logs from the system. As previously mentioned, your experience is not common, so help us, help you.
Lastly, the new firmware that I mentioned 14 days ago is planned to be included in the next major platform update (2.4.4). Until then, you are testing the same firmware, so why would you expect different results?
Oh, I am sorry, I did not provide a details on when switch to ZWaveJS was done and attempt to exclude few devices. These two events are a week+ appart. I tryed to exclude already unused but still (battery) powered devices: Fibaro Multisensor (this was a single device included with A0 security) and two Ecolink Contact Sensors. Eventually all these devices were excluded but it took too many attemps. The problem was: most of the time the Exclussion Process stopped abruptly before I took off my finger from a mouse button. I am sorry, I did not watch any logs but I am almost sure there was not any errors.
Many users are very happy with ZWaveJS. I decided to cleanup a bit the ZWave Mesh and to try again ZWaveJS. The cleanup was done after the switch (maybe it was better to cleanup mesh first). Of course, the random delays instanly started to pop up. For the Ultraloq Lock I had to create a lock/unlock function rules which are called from the main rules instead of a simple commands. For some reasom Ultraloq Lock almost never report an updated status but doing a "refresh" helps a lot. Here one of the function rm rule:
Also after a while few Zooz Switches which had these random delays stopped to respond all together. Performing a "repair" for these devices cleared the problem. I wonder should I run a global ZWave Mesh repair? I know this, is not recommended but doing individual repair for each device will be too anoyang and time consuming. However now I am doing individual repair for each device which exhibit a random delay. This seems to be helping a lot except for the lock.
Recommended, necessary, and effective practice often blur together.
In reality, rebuilding the network manually is not necessary, as the C-8 Pro radio does that on its own quite frequently, thanks to the improved 800 series.
Is not recommend practice if the mesh is unhealthy, as running the network rebuild can leave the mesh in worse condition, or cause the network to become unresponsive.
Is not an effective practice because "repair" doesn't magically fix anything, rebuilding the network is merely forcing the radio to find better routes between nodes, but is already doing that on its own (see not necessary point above).
Greater effort may need to be spent on individual devices and their firmware, and to make sure they can communicate properly with the hub.
Now I am confused.
With the ZIP the ZWave Mesh had next to zero issues.
With the ZWaveJS (which should/must be much better) there is a BIG problem with the Ultraloq Lock (but most likelly this is a problem with the lock itself, not HE) and well noticable unoyang random delays. Furthermore, instaed of self healing over time few devices simply stop responding. Gladly the individual "repair" took care about this issue.
So, what is your recommendation for my speciffic case?
I really would like to stay with ZWaveJS.
Should I ran a global mesh repair (overnight) or whatever else?
Bobby is the boss/expert here, but if I was in your shoes, and knew that new Z-WaveJS firmware is "coming soon," I would hold off on migrating from Zip for now, and wait for the new firmware. Might help you skip some of the issues you're experiencing.
If the firmware's arrival is accompanied cheers of joy, then try to migrate to it again.
Same as 14 days ago. Let's wait to see if the next update resolves the problem. Until then, stick to what works best for you. I know you're excited to switch over, but what good does it do if it doesn't improve your experience like it does for many users?
Actually, except for the Lock (which I tried to fix with a very speciffic rm rules, maybe it is a time to try writing a custom app) the ZWave Mesh behaviour is getting better. But for some reason it takes a lo...ng time vs. expected few days. Plus for the Devices with the long random delays (the majority if not all are Zooz Dimmers) the individual "repair" takes care about the issue (so far so good).
So, for now I will stay with the ZwaveJS and wait for the next platform release.
And just to close this discusstion - should I do a global mesh repair (overnight?) or simply wait for the next release?
Thank you very much for all your attention and help!
Maybe because I switched between ZIP and ZWaveJS multiple times last switch back to the ZIP did not remove/improve all that random delays like it did before. The only Lock became happier with the ZIP. That is why I switched to the ZwaveJS again and sort of "fixed" lock behavior with two extra rm rules. It looks like switching between ZIP and ZWaveJS some how stressed the ZWave Mesh. Maybe the ZWave Mesh has some sort of hidden problems but I cannot figure out what it could be. All the Devices are working just fine and how random delayes are poping up regrless which ZWave stack is used.
I've switched back and forth a number of times in the past and didn't find any difficulties doing it (they use the same database) other than the already noted factor of Z-WaveJS needing some days to settle. After one of the updates a month or more back things were initially very unsettled for me.
Like much in the home automation space, very much a YMMV situation, as everyone's mesh is different in terms of device brands/specs, device types, device count, device placement, use, etc., etc. 
Persistent random delays are usually a sign of subtle mesh issues which can be hard to troubleshoot. Time spent in Logs (Applications and Devices sections) can help ID devices that may be hogging bandwidth... I currently have a sporadically delayed automation that I have to investigate, but it's infrequent and not significant (1s) so I've been too lazy. 
