This ^^^^^^ is me, precisely. In fact I was just thinking, this morning, of removing our R3 from HomeKit and moving the app back off to a corner, somewhere, because we don’t use HK for anything anymore.
I only brought HK out of storage and re-added our R3 to test connectivity. Well, it’s been nearly three months (I re-added our R3 to HK on May 17) and… <checks…> it’s still there. It’s been there, and been working, every time I checked. This is through multiple brief power failures, forcing the R3 off one AP onto another and back again, and forcing the HK server to switch. Just started-up a zone that has an area freshly-seeded two weeks back. It’s running and the zone is updating the remaining time in HK.
I guess I’ll leave it for the entire three months and then remove it and re-retire HK.