Based on tens of thousands of rounds I've fired through my 5 personal GC & NM (1 pre-war, 2 series 70 & 2 series 80) sampling over the past 40 years, I would argue that Colt match handguns make find combat handguns.
While the Accro and Eliason rear sights are a bit fragile (the newer dovetailed Bo-Mars would be better in that regard), the remainder of the gun, including the fire control bits, can take all the abuse you can heap on it and still function quite reliably.
Yes, some of the older guns required a bit of ramp and throat work to feed HPs reliably (especially the old Speer "flying ashtray" bullets) and can be picky about what magazines are used... but all in all, I don't feel that a GC, in most of it's guises, would be out of place as a defensive pistol. My late father, who carried a National Match in WWII France would probably agree with me.
I think... and this is an educated guess on my part, that many National Matches and GCs have been "fiddled with" over the past many decades by folks that don't really know what they were doing (me included in the 70s
), consequently there have been lots of guns out there with botched trigger jobs, slide "tightenings", ridiculously stiff recoil springs, 2PFLGRs and other "modifications" that only served to make the gun less reliable.
Cheers,
C