Mainly because I was having more and more problems with the 3 related to storage (I have lots of plugins). For example insufficient storage to do a firmware update. Had to factory reset on the 3, update firmware, then restore from backup. But then the restore failed repeatedly despite many backups to try. Took MCV support almost a month to get me back online. ZWave backups were also failing regularly. And on and on.
Good news is I got the Plus on sale from MCV. Followed the upgrade instructions. Read all the tales of woe from others who upgraded. Mostly the upgrade worked quite well but I had to manually include (as new devices) some, but not all, of my battery operated sensors. Not much of a pattern to it. I waited about 3 days for the Plus to catch the wake up events from the sensors but mostly they just weren’t home. I guess that’s not totally accurate. The ZWave definitions did transfer, but notifications (events) were still going to the 3 and not the Plus. Just for some battery devices, like motion and door sensors mainly. But I was able to delete and then re-add them manually to the Plus, then just had to update some scenes and PLEG configs with the new devices.
And as always AltUI just works. Couldn’t be happier and the faster Vera Plus makes the UI just slightly snappier. Or maybe I’m just imaginings that. But I like the ‘it just works’ part. And the ZWave backup on the Plus now takes just seconds where I would wait 20 minutes on the 3–if it worked at all. Some day soon I will try a factory reset and restore. I hope my experience with the restore failure from multiple backups was just a fluke.