upb switch replacement from SA

[rismoney]

I currently use homeseer and only have UPB switches in my house.  They are all simply automated 11-40 switches installed about 10-15 years ago.
I need to now install a 3 way application (redoing the garage), and thought about (not sure if they are good switches or not), but seem popular, Z-Wave switches.  Is Z Wave the prevalant go-to switch now?  Looking for the same level of reliability.  I haven't looked at this stuff in ages.
 
With the 2x11-40's you can use them in tandem instead of using the "dumb" remote option (DD00R-DL?) to create uniform switch usage in the house.  Is this possible with Z waves?  I started looking at Leviton dz6hd or a dz1kd (not sure difference) and wiring diagrams only mention remotes/traveler wires.
 
If there are better/reccomendations or approaches I would definitely be interested.  From what I see, I can't just get Simply Automated switches anywhere.

 

[bbrendon]

I also have SAI and happen to have one HAI switch as well in my house.  Ever since the Pandemic I did hear production of SAI came to a halt. No idea what happened there or if they have made progress getting operations back.
I think ideally you would stay on one system. You might find other brand UPB switches out there. Also, have you tried contacting Terry at webmtn.com? He might be able to help.  
 
Also, looking on ebay yield some results.
 
I've never used Zwave myself but I've read plenty of horror stories. I would guess though there are many more horror stories relative to UPB just because UPB is very uncommon.
 
I'm not sure a Zwave system can last an infinite number of years without having to repair all the devices like UPB can. The Zwave hardware or software maybe be limiting factor there.