There's definitely more room on an SS. I rode several monsters last year and they were all quite a bit more cramped. Having said that I still can't feel my feet at the end of a race!
I'd go for an SS and splash out on some adjustable clipons/rearsets if possible.
The price you pay for the extra space is slower steering (ss?? coincidence???) , something I still haven't ironed out on the SS. Even flat out over the crest after druids didn't generate anything more than a slight shake of the head. Great for high-speed circuits, but a pain in chicanes.....
Cheers,
ali