If you dig deep enough in the forums you will see that most of us experienced pain at some point! We can sympathize!!
I migrated from SmartThings last October and had a very tough time with migration. I had to reset my hub a couple of times and re-pair all my (120+) devices - good times. Now things are running great and the WAF is on the upswing...
One big issue for my was my Yale YRD256 z-wave lock. Had lots of difficulty pairing, keeping connected etc. Ended up replacing the module with a zigbee one and everything started working as expected. Locks seem to be tricky things with HE for some reason.
There are a lot of factors in play when setting things up (device type, distance from hub, interference factors etc) - check out the Iris threads, there is a lot of good advice from some very smart people.
