I've been rained on in Upstate New York, Vermont, the Southern Arizona Mountains, and now western Washington in my Tepui Kukenam Sky. Never gotten a drop of rain inside the tent. The Sky feature was especially nice during my brief tenure in AZ. Just my $0.02.
I should clarify my previous comment: I mean that less zippers and seams means the tent will stay weatherproof longer. I'm sure these tents are waterproof in the first place. Depends on how often you camp, and how careful/abusive you are with your gear.
My gear all looks like crap after a single season!
A.