These bikes already sit pretty low. I'd worry about losing even more ground clearance. Other than that, I think it's a great idea. Run a search for Buell wheels. There are a few street rods out there that have done it
Did mine a couple of weeks ago and they are great. They do lower the bike 1" in the front and 1/2" in the rear but they are much lighter than stock wheels, about 30# and you can run some awsome 17" street/comp tires. The Buell front perimeter brake is very good too.
I just did mine this weekend, but I went with chain and sprocket instead of belt and pulley for drag racing purposes. I love the wheel conversion. Although it does lower it quite a bit. I know it is only 1", but 1" sure feels like alot. My only concern is that the kickstand might need shortened a little bit. Since I am mainly at the strip I am not worrying about it much, but when you go on rides and don't always have the best parking surfaces around it might become a factor. I also have 12" shocks inthe back and the tubes poked thru the forks on the front so that might play a part in it not leaning over all the way.