Well, if the 1100 could go fast we might hear about the 'happy feet' the sublime 1300 has, but since it doesn't, we only know about the decel headshake the 1100 exhibits. What's that about? UNSTABLE AT SLOW SPEED? As long as you don't hit a parked truck with it and get on the internet it won't earn an undeserved reputation for having the shakes.
Don't want this to degenerate further into an argument about the 'superiority' of the ST13 over the ST11 by those who feel thay have to do such things for some reason. People have picked their bikes for various reasons, some have chnaged and others gone back to older models (not just for STs, other brands and models included).
I assume by if it could go fast you mean some acceleration advantage due to the lower gearing and a bit more power of the ST13? Top speed of the ST11 is 141mph and the ST13 144mph, going by some UK tests, so I don't think 3 mph is much less speed
The ST11 seems to have as much headshake as the ST13 has high speed death wobbles. Haven't seen report of anyone killed because of a bit of headshake. And I have not seen much in way of problems from civilain ST13s fully loaded up, so don't see it as much of an issue in practice. BTW, my ST11 has no headshake.