I have a 6" stainless GP-100.
The trigger, while heavy and gritty at first, is really not bad compared to something like a Taurus.
It will smooth up nicely after some shooting but will still be heavy.
I just replaced my trigger return spring and hammer spring with reduced power Wolff springs and I also took the time to carefully polish some parts with a very fine ceramic stone.
The result is amazing. The trigger pull is just as good as a well used S&W but still a tiny bit longer (can't fix that, it's in the design).
I still have to take it to the range to make sure its reliable with the reduced springs.
I also put on a Hogue rubber grip. It felt funny at first, but now I think I like it more than the factory grip because it's narrower and I like the grip angle more.
You won't be dissapointed with a GP unless you're looking for something lightweight.
A local gun shop owner I know used to work at Smith and Wesson. They tested a Colt Python, one of their S&W models, and a GP100 using the heaviest handload .357s they could make, to see what it would take for the revolvers to blow up.
The Python was the first to blow up, followed by the Smith. They never could get the GP100 to fail.
That's nice to hear from a former S&W employee
But...If you read posts made by Clark, I believe he said that the GP-100 doesn't handle destructively large loads as well as the other brands. I do not remember the models he destroyed, but he said the GPs will fail before the others.
Keep in mind that he loads to insanely high pressures. He also said that while it won't handle as high of pressures as the others, the GP will not shoot loose with very heavy (but not heavy enough to cause a blow up) loads while the others will.