I had one put into one of my competition 1911's, a .45 Springfield Loaded. I was a little hesitant at first, but the gunsmith said he used them exclusively and has never had a problem. It actually made the trigger much "crisper" and shaved about a pound off the trigger pull. Clark has long been known for good quality custom guns, and now I think the parts are just as good!
I don't know if one would work in a GSG, is the sear the exact same as a regular 1911?