I've built one Mach 2 kit (their F2Y Sea Dart) and own several others (including the S-51)that I'll build when I'm absolutely certain that no other manufacturer is going to do the subject or hell freezes over, whichever comes first.
Actually, the Mach 2 kit doesn't look too bad in the box relative to some of their other efforts. However, I suggest that you get the MPM kit instead. It will be a lot of work too, but I think you'll have a better model for the same effort expended on the Mach 2 kit.