I'm sure this topic has been covered before in other guises.
A friend of mine, not on this site, recently purchased a CBR600RR, and after riding it for the first time experienced various aches and pains to his wrists and shoulders and who knows where else. He went from a fairly good-natured bike (GS500) to a full-on replica complete with aggressive ergos, and seems to be be paying for it physically now. He's in his 4th season of riding.
He seems a little discouraged, but this only after the first ride. I told him the body will get used to the new riding position over time, and to try to hold his upper body weight more with his torso/trunk while squeezing with the knees, rather than letting all the weight shift forward into the neck, shoulders and wrists.
I have heard of people modifying their sport bikes with handlebar risers, Corbin seats, gel seats, hair gel, hairspray and whatnot. But is all that really necessary? My belief is that the more you ride, the more the body adapts to the new ergos and aside from any congenital or other pre-existing medical conditions, there is nothing that mileage in the saddle can't take care of.
I occasionally ride 400 - 800 kms on a ZX6R, and am only in average physical condition. It wasn't always comfortable though, I remember the first long rides when my left hand ceased to function after clutching for 8 hours, but all that seems to be mostly gone now.
I might be missing something here, and ask for your thoughts.