Having ridden the 1150, you should be more than capable than anyone on this thread to judge if you still wish to go for a used one. Obviously you ain't gonna find new ones so the 1150 beats the new 1200 on price alone.
However the 1200 does feel lighter, sporting add ons and upgrades over the 1150 that you can easily search for on the various online motorcycling editorials around.
The general consensus of the blokes on advrider.com is that the 1150 is evolutionary over the 1200, but certainly not REvolutionary.
As such, since you've had your fill on the 1150, I reckon yo