Recently picked up a 4x8 "Ultra Yield" tent. It seems like a good tent, but the only thing I can compare it to is my old 4x8 made from 2x2s, 2x4s, and panda film.
I won't be running a grow in the tent until this summer, but it was pretty easy to set up with two people so moving it shouldn't be a problem. It does seem to have a heavier duty fabric, as well as double cinching exhaust ports and an included 1 ft extension that brings it up near 8' tall. When I zipped it up and got inside, I noticed no light leaks whatsoever.
So far I am satisfied with my purchase, however, I still haven't put it through daily use so I'll hold off on recommending it until I have. I paid $350 for the 4x8, but it has since gone up a bit.