I've got WebCoRE running fairly stably myself with over 60 pistons, running the webcore piece in a container locally. It's not without a few tweaks and workarounds, but I just don't see being able to do the sort of complex things I want to do with RE. I mean, the pseudo-code of webcore is bad enough, an even pointier-clickier drop down interface fills me with dread. If I could just write my rules in something like python or ruby, with Vi, I'd be happy as a clam...
Getting WebCoRE working has not been without its trials. First off, be very careful with @globals. If you use them extensively, you may need to force resume some pistons in order to force them to pickup changes made by a different piston.
Secondly, many have complained of slowness, and I've seen this at times as well. I don't have a great picture of what's going on with that, but I've discovered that for me it seems to be related to adding new devices. I've developed the rather annoying but seemingly effective practice of, after adding a new device:
Ticking the disable all pistons switch
Rebooting with out the radio stick
pause all pistons one by one
reboot with the radio stick
resume all pistons one by one
I don't know why this works but it seems to vastly speed up webcore, and that speed up seems fairly durable over time. This is of course annoying when you're initially adding devices, but once you've gotten everything added its not too much of a burden.
The other thing is I'm still running 1.17.20. I upgraded to 2.0 the day it came out and my hub crashed later that night so I rolled back. Maybe related, maybe not, but I'm sticking with what seems to work.
After about 3 weeks I've got 1 or 2 logic bugs left in my programming, and one or two devices that behave somewhat erratically. These are cree bulbs who's state gets confused with what Hubitat seems to think they're in. The singled bulbs don't seem to have this problem like the cree ones do, and it might be related to issuing commands to them as members of a WebCoRE device variable. I've just tried addressing them individually this morning and we'll see if that clears it up.
Once these last few issues are cleaned up, I intend to leave the damn thing running in the closet, untouched for the next 3 years! No updates, no tweaks, just glorious stability! Frankly that, IMHO, is the true glory of hubitat. Nothing changes without my consent.