I don't own and haven't ridden a 10R, but I can make a good comparison with the 636...
I own a 2000 9R and my good friend owns an 05 636. She just bought it new this season and I was able to ride it a little. After being on my 9R, the 636 felt like a damn scooter. I HATED it. It felt like it had no torque whatsoever. Granted it was in it's break in period so I babied the hell out of it, but still, I think that made the power difference stand out even more since I don't ride like a madman anyway. I can comfortably ride around all day long on my 9R and never go above 4000RPM unless I'm doing more than 65mph on the highway. On a 636, if you don't get the bike above 4000RPM (which is the recommended break in RMP limit) you're barely going anywhere, and that especially includes the highway. Don't even get me started on going uphill in that thing...
When I eventually get a track bike, it will no doubt be a 600cc. But for the street, there's no way in hell I'd ever buy anything less than a 9R. Again, I don't know how the 10R is, but I can only imagine that it's about 1000% better on the street than the 636 (at least for me it would be), just like my 9R is. If it were my choice, I'd take the 10R hands down (and ride it VERY responsibly so as not to kill myself).