There's a very basic intro to bike geometry here:
http://www.australiancyclist.com.au/...aspx?aeid=4537. The tires will make a difference too, but a couple of degrees in the head and seat tube and 2cm in the chain stays makes a difference you really can feel.
I have no idea how the the sst will handle. It's chain stays are almost as short as the Moto's, but it's head and seat angles are the same as the middle sized 925. You'll have to let us know what that ads up to.