I rode an RSV-4 a few years back, brand new one, it was horrible, the whole thinng rattled, V4's are gross.
Really that bad. There was someone who did a nice write up of why inline 4s were better than v-4s. It mostly had to do with the firing order. But then I wonder about the MotoGP V-5 cylinder bikes that have the strange 5th exhaust pipe coming out of the side near the middle. At least I think they are v-5s. That might alter the firing order to be smoother than a v-4. Those are one off bikes though.
Floyd