UPA-1: You'll miss 1 extra HDMI input port, lack of HDMI 1.4a support (no 3D support or return audio channel).
Instead of highly elaborate "Audyssey Mult EQ Pro" Calibration Compatible/Installer Ready you get "Emo-Q" which I'm not sure how is it since I haven't seen any reviews yet....
UPA-1 is relatively fresh product on the market and first pre-amp emotiva ever made and initial launched product was affected by multiple bugs, which were ironed off as time went by.... (according to latest reports from owners)
The rest of differences are minor, however with UPA-1 you potentially gain Higher quality pre-amp and Emotiva amps are notoriously getting highest results in all reviews...
I'd also take a look at Pioneer Elite VSX-33 for comparable product...