I don't have experience with those 2 exact models but really, all Buells (XB's) are basically the same except for cosmetics. The differences in ride between the 2 will be minimal. The biggest difference in ride comes from a Firebolt vs a 'standard' (Lightning, TT, SX or similar), namely because of the more leaned-forward riding position of the Bolt.
In my experience with 9 vs 12 (I've owned both):
-The 9 is slightly less "Vibey" at speed.
-The 9 revs faster and higher and, to me anyway, is a far more enjoyable engine to 'play' with.
-The performance difference is there but not Earth shattering.
All in all, I enjoy the 9 more than a 12. I currently have a 12R because an 04+ 9R is VERY hard to find around here and I don't want to deal with the belt issues of an 03 or fork over big $$$ to convert an 04+ style belt.