I am form UE thinking about having AVP taking advantage of my ETHDENVER trip.  
What's the experience like working with them? I mean, for several hours at a stretch. The screen quality is surely great and the size amazing, but I'm worried it might feel a bit like sitting in the front row of a cinema.

It’s been pretty good, for long stretches I suggest the overhead band as it relieves some neck strain. You can also resize the screen to whatever you like and play around with depth so it feels like a floating screen and not a movie from the front row