aside from the bore-and-stroke differences, the compression ratio increase really jumps out at me.
All other things being equal, increased compression is a great way to more power, as well as capping the overrev slightly.
Combustion chamber and squish design are a complex interrealation of many variables, but generally speaking, the more comperssion, the better the BMEP (brake mean exerted pressure), which is the measurement of how much 'push' is exerted on the piston per measured quantity of fuel burned.
I WAS concerned about running 12.5:1 on a street engine, but not so much anymore...if it's good from the vaterlandt, it's good enough for my 11S (with the proper state of engine tune).
Yes, I know I'm beating a dead horse here, modifying an 'obsolete' R1100S, but I tend to keep motorcycles for a very long time.
I'm stubborn AND crazy
....the perfect combination for a denizen of this board.