My only issue with the presence tag right now is the clasp isn’t strong enough in the current molding. (I know it’s going to be fixed here and I will get a new plastic case for it.) but it’s made me hesitant to give one to my wife to use yet - especially with a little kid who likes to take her keys - etc. 
I did get the GE z-wave switch working with an electrician last night… fortunate to have a friend with an electrician friend whose commute takes him really close to my home. Anyway - the 3-way GE kits WILL NOT WORK if you do not have a neutral wire. Andrew - you said the dimmer will work without it (which is great to know! The single switch should work just fine without the neutral as well…) - but you cannot use the 3-way kit without it. I had to “un-3-way” that set of switches - so I lost one switch - but hey, it’s worth it! I have one more set of switches to check out tonight when I get home to see if there is a neutral in there - and he will stop in and put them in for me if they do… but otherwise you are hosed if they aren’t in there.