If your short and want to lower your ride to get better footing I can understand that but why else would you want to put shorter shocks on. I'm looking at changing out the shocks on my 06 1200 c with some progressives but cannot figure out why almost everyone who does this goes with a shorter set. for those who have please explain. I'm thinking on going longer to get a little more travel.....
I would say just for looks. I personally like the look of a lowered bike, but, not as good in the twisties. I go fast enough in the twisties to put a smile on my face, and I have no problems scrapin. But then again, I don't drive it like I did with my crotch rocket. If you like to really lean into the curves, stay away from the shorties.
When I went to progs I installed 11.5" (stock is 11.75") because they only come in 1/2" increments. I didn't go any lower because I like to ride twisties and already have to be careful not to drag my lower pipe.