Corey: I have several sets of wooden Altamont grips. Been using them for 5-6 years, now. Checkering is fairly aggressive. Though well executed. Very positive gripping surface and no slipping, at all. I use them in cowboy action competition on a regular basis...often under hot and humid conditions, without issue. I like them.
Though I also have Eagle Gunfighter grips on a couple of other Ruger Vaqueros, and like them too... despite being pricey. I would not hesitate to purchase Altamont grips, again. Great value for the money, in my view.
I have no firsthand experience with the plastic Altamont grips, so can't offer an opinion on them. Perhaps the smooth grips might slip. Depending on how sweaty a person's hands were. But, going by the checkering on some of the other models, I can't see where there would be any problem with grip.
Hope this helps
Al
ps: By the way, I like the selection of Altamont decorative grip styles. Stylish, with a good variety to choose from. Hardest part I had when choosing which grip style to buy, was the pattern and checkering execution that appealed to me the most. Easiest part was choosing between slim, versus fairly hand-filling grips.