The rear seat does look kind of small, but fortunately I don't have a problem, my wife hates and won't get on the back, so for me it's a seat pod and no rear pegs.
It's worth testing both bikes two up, but the question has to be how often you ride with a pillion, if not often then go for what you like best, if often, then may be best for the more practical option.
I actually made a huge mistake in 08, when the wife muted she may now like to come out on the back but not on my then K6 GSXR1000, so I traded it in and bought a new Bandit 1250 GT with full fairings and panniers so we could tour together, one short run and she said never again!!! So after 2 months the Bandit was traded against a new 08 R1, which I never really liked the feel of as much as the GSXR, so really wish I'd tested the Bandit with her on the back, as probably would of kept the Gixer a bit longer! Lesson learnt.......