Deaf
So far, they've held up just fine to magnum loads.
I've run a bunch of 158-grain magnum stuff through both of them with those grips and no problems.
I got them because I want to occasionally carry the GPs on a belt holster, and the Lett grips (and other rubber grips) are sticky with regards to my cover garment.
As to the wood, I think they're mahogany, but I'm not a woodworker or anything, so it's just a guess.
I can tell you that they look great up close, and the guys who run my local range liked them a lot. They really bring out the looks of a GP100.
lc