Having had 5 rugrats myself, with carseats and kid crap, the extra room will become essential if you can make it work garage-wise (I would hate my truck sitting in the street). Remember, measure twice, cut once. But hey, you need to take the whole family and all the associated clutter, take the Tahoe regardless of which truck you buy.
Interesting question about the door configuration and safety, although I would think that if someone T-***** you, most cars would hit you lower than the center of the door, nearer the bottom sill, where the truck is uber stiff side on. Big truck T-Bones you at high speed, all bets are off. As for the seat angle, the SCrew is very comfortable for looooong periods, I'm talkin 5+ hours comfortable and adults in the back. Seat is big enough to turn into a cot to snooze too, and I am 6'. Still no rear seat adjustment in the SCrew, it's just comfortable. As far as access, the SCab, might be easier to access back seats with kids and car seats, the doors on the SCREW are HUGE and cut a pretty large swath. SCab might be better there, maybe someone will weigh in on that.
Bottom line: Quit ****** around and decide already! We expect to see pics SOON.