I wrote an update on the Kwikset Convert deal post but thought I should write one on this thread also.
I finally received my Kwikset Convert, and its zigbee module was indeed swappable with the Z-Wave module. I was able to pair the device without much pain. It defaulted to a generic Thing DH. I switched it to Zigbee Lock DH in IDE. I can also confirm the rboy lock user management smart app does work with the Zigbee Lock DH. I installed the module and paired on Saturday. It is now Monday and everything appears to still be working ok. I don’t believe it has gone offline at all throughout this time.
Then, out of curiosity (and didn’t want to waste the hardware), I also tried plugging in the old Z-Wave module into the Convert and install it on my back door. It did not pair initially but while pairing my Z-Wave repeater nearby, the Convert also popped up during discovery. The back door is quite a bit farther away from my ST hub. Strangely, the problems I was having with the module on my 910 is not happening in the Convert. The lock hasn’t gone offline since installing it a couple days ago as far as I know.
Edit: I spoke too soon. The Z-Wave module in the convert is acting strangely. I unlocked the deadbolt manually, but the ST app wasn’t aware of the change until about 50 minutes later. What’s different this time is I can control the lock still from the app instead of removing the battery and reinserting it like in my other lock.