These are really differnet guns. Outside of being both full-size and if well maintained both solid guns, they are pretty much at different ends of the spectrum. Anybody who appreciates revolvers would go for the GP100 I would imagine. But what do you like and what would you conceivably want to use it for? I personally would think the GP100 would be more fun to shoot at the range but also more expensive, especially with the 357s. It's not really a CCW although a full-size M&P isn't either. For me they fill completely different roles.