I also have a Mutant short, and a Rapid 70 kit added to my Prod and a bunch of other modifications done to it as well. Sometimes I consider selling the Mutant just because I find the Rapid P easier to aim, smaller, lighter, and just as accurate (although at much shorter distances) and I'm also not concerned about it getting bumps and bruises like i am with the Mutant. The Mutant is the far superior machine, with much more power etc but I can't honestly say that I like it more. When I purchased it the Rapid mod was already done to it so I cant comment on if it was better as a pistol or not.
Pic's next to the Mutant Short