I had Joe put two draft tubes on mine, since I wanted the zipper on "top" (actually in front, since I'm on my side). The zipper does occasionally snag, but since I'm aware of the potential problem, and don't just mindlessly try to zip or unzip, I seldom have a problem. I usually put my thumb or finger just in front of the zip, and things are fine. If it does snag, I don't try to force it, but back up, push things out of the way, and continue. In my experience, it doesn't really snag much more than any other bag I've had.
FWIW on size, I'm 5' 10", 195 lbs., and got the long (6' 2") wide version. I got the extra length because I've found that sleeping on my side in a semi-fetal position seems to suck up extra length of a bag with the extra bends to accommodate. Fit and temp ratings are fine.