I just did an RGV250 shock swap (my old one had become mush), and much like Leveller said on the UK board, it drops straight in. However, it does raise the back end up a couple of centimetres, enough to make the bike lean over significantly more than before, and the rear wheel have very little clearance on the centre stand (I think this is much like the GSXR boys?). However, adjustable preload and damping via the trick remote reservoir more than make up for it. The rear end simply doesn't drop down under acceleration anymore, and is much more stable in corners. Turn-in is faster too. In fact, I really need to get the front end progressive springs in, because the backend now dwarfs the front-end for stability.
Australian and UK peeps should be able to source RGV250 shocks without any trouble from wreckers, due to the horrendous amount that have written themselves off!