Years ago, SmartThings groovy changes pushed me over to Hubitat. I still kept a few things in ST, which eventually led me to build HubiThings Replica so the two could play nicely together.
Now SmartThings has upped their game again by charging for API access and pushed me into Home Assistant + Hubitat!!
And annoyingly it turned out to be a great move. I am now almost entirely local, have way more options using the best parts of both HA and Hubitat.
At this point I’m starting to think SmartThings real product is helping me discover better home automation platforms. 
Gotta give them props. They have been very consistent.
For the few things such as appliances that are still dependent on SmartThings there is a new local integration over there that is ramping up called LocalThings. This came about due to the paid API requirements.
Yes! Running LocalThings for the appliances and the Samsung TV integration package. Much faster and has a lot more features that the cloud ST API solution provided. Highly recommend.
That is on my list to implement before October 1st.
That is a common story I have heard a lot. SmartThings seems to a place to stop by for a year or two, and then move on to greener pastures. I went to SmartThings when Wink started charging, and then to Hubitat when the Groovy cloud was about to be eliminated, and eventually added HA using HADB.
I know we get people who give their goodbyes to Hubitat here as they move everything over to HA, but I also really like the mix of the two platforms, taking the best of both worlds.
I am the same way. I use HA for devices that either at the time I could not connect to HE or some problematic devices on HE. I use HE for all automations, most Zigbee, all Z-wave, and most HomeKit. Like you I like having the mix and being able to use HA for those outlier devices and bringing them back via HADB.
I never was a SmartThings hub user. I went from a horrible failure as Alexa being my hub to HE. I only have used SmartThings in HA since November last year for a stove and fridge. I have had my full of them with this limited stuff this quickly. lol
Loved ST 7 years ago, then Samsung acquired them and they ruined it! I departed for a emerging company called Hubitat, with local processing, hub cloud & local backups, remote access, hub protection, with new and faster hubs, RM for easy automations and groovy for my integration/development. I have never looked back departing from ST and I am very happy. (Note: I have two Samsung 2026 TVs that have internal ST, but I only use it for TV api access/control.
Currently I have 5 HE hubs ranging from C5, C7(2), C8, C8-Pro) using Hub mesh for synchronizing, Matter integration for Apple HomeKit and Quara hub, several thread Border routers and Home Assistant working together. Quite happy!
Thanks Hubitat for being a rock!
Fairly large ST supporter here, so I'm biased. That being said I am migrating away from our primary managed installation that was ST + HE towards Home Assistant. The HE side has been shutdown and all the integrations it was performing moved over to HA. All but a couple Zwave and Zigbee devices have been moved over to HA.
My other installations that aren't as diverse or just need simple mobile app dashboards that just work and some simple monitoring (ie, parents/inlaws/work locations) are staying ST. I don't care about the API-fee-structure because I don't use it in those locations.
ST still gives a solid framework with cloud based mobile access and a good local development and routines environment for most devices all for the low low cost of zero. We'll see how the API fee structure shakes out once it rolls out in a few months.
I didn't have the attachment to the good ol days before Samsung ruined it because i was never a WebCOre person and I still think that Groovy just sucks. When ST moved away from Groovy to Lua/Edge I was excited and still like developing in Lua.
OTOH, a SmartThings V3 hub can still do Zwave, Zigbee, Matter and Thread (1.4 even, so it can join other Thread networks) for a very reasonable price used. Still getting firmware updates (yes i know you can't schedule/opt out). WAF was always super high with the mobile app.
Anyway I give props but from a different POV. I still find a lot of value in it and in many ways more than HE.
I had some time this morning, so I went ahead and setup LocalThings for my refrigerator and range. I have to second what you said, the response inside HA Dashboards for indicating state change is noticeably faster. Maybe a half second to a second faster on the dashboard update. Also, there is many more features.
I was surprised at how easy it was to setup. Getting the certificates and key was not as complicated as I was afraid it would be. I spun up a small VM in Proxmox and used it to pull the needed items. Once LocalThings was setup in HA I destroyed the VM.
Its early I know but to this point I would recommend anyone that uses SmartThings in HA to look into it.