I’ve bought many kits from mcarbo for various guns . I’ve done trigger jobs on various guns myself, polishing , removing material, etc.... the mcarbo kits for the money are great. I’ve actually got a gp100. And I’ve considered buying their kit. I’ve used a shim kit of there’s before in another gun and it worked wonderfully. I wouldn’t be to scared of their lube either with ptfe.... it’s good stuff , better than previous grease I had been using which was birch wood and Casey brand. I’d go for it and get the kit. My gp100 trigger isn’t bad to begin with so like you said I don’t know what polishing would do for it, but I do know for a fact in other trigger work I’ve done polishing does make a difference sometimes. “Sometimes”.... is the word. Depends on if the surface is already real smooth to begin with.