Depending on where you live, it might be better to stick to the EMT, since the PVC Sched 40 pipe gets a bit brittle in cold temperatures in my experience.
I am on Chesapeake, it is not cold enough for that around here. I used 3/4" EMT previously but it is a bit tough to work with. I used 1/2" this year - easy to work with but not as sturdy.
Plus, with PVC there is a better variety of connectors - for example there is a 4 way socket, so I can easily make connections on top of arches for the forward-back rib, there are angles etc.
Anyway, I am not set on that - gotta go through this winter first.