I used an EZIO8T for garage door control early on using 24V AC relays to switch the door opener. Never had a failure. Eventually changed to EZIO2X4s when they became available as I wanted more digital sensors and the 2X4 relays could be used directly for door opener control.
Have more years of use with other EZIOxx devices with no relay failures either.
Without any failure pattern to point to I really cannot say which would be better.
The EZIO8SA relays are spec’ed at 3A which is more capacity than the .5A Triacs in the EZIO8T. The EZIO8SA is more expensive per available relay. It would seem the .5A Triacs would be more than enough to run Zone valves. The EZIO8T would be easier to install as it is all contained in a single SmartLabs shell. The EZIO8SA has the external PLM as well as a separate package for the 8SA function.
Sorry but I don’t have any objective information either way. I think either would provide a good solution.