I've owned both. I had one of the first Match Champions to hit and it looked like it was built by Stevie Wonder and finished by Ray Charles... When Ruger got it back in house they called to tell me that it never should have been allowed out the door. That said, they built me a new gun and had it back to me pretty quick (less than 2 weeks IIRC) and it was fine. The gun shot well, pointed very well and was robust. I had the early model with the fixed rear sight. That always bugged me. The wood stocks on the MC beat up my hand so I used Pachmary grips... and the stock front sight on the MC was NOT a quick change unit like those on the standard GP100.... I ran the gun in IDPA and it performed very well.
That said... my '96 GP100 was smoother, had the quick change front sight and an adjustable rear sight and I didn't pay extra for the wood stocks so it didn't bother me to put pachmayr grips on that one.....
For the money I would buy a clean, standard GP100. They are a tough, stout, robust gun... I shoot Smith & Wesson 686SSR's but the GP100 is a fine revolver. Given your intended use I think you would be very happy with one. As a buddy of mine always says, "It's a Ruger... you can shoot roofing nails through the thing and you won't hurt it".... I tend to agree.