It's not just the resin, it's the fiber. G-10 is glass fiber, which is very nasty stuff. For me, and I do boats also, I simply won't grind that stuff indoors under any circumstances short of HASMAT level precautions, which would be seven different types of extraction. What I most want to avoid is any dust just around the place, cause like having loose asbestos fiber, it will prgressively wear you down, when you are just hanging out in the shop. And I wouldn't grind a lot of it outdoors either, you're just creating a superfund site. I have kids around, so I'm not going to stick it to them outdoors. If you do extract it, you pretty much can't recirculate the air, and I used dedicated Hepa filters. So I am not spreading it when I am just dusting up corn chips.
I'm not sure what is in any of these resins, other than genericaly. But a lot of the resins are made of materials that if properly prepared, are pretty close to inert when they have hardened. What you want to avoid is any smoking or cooking that is clearly releasing compounds. You don't necesarily get 40 years of exposure with this stuff, ask a fireman. On the other hand, the dust alone may not be all that terrible (resin dust, glass or carbon whole other deal)
So I would prefer to deal with diamondwood (sadly no longer all that cool), since the resin isn't always bad. These products cut, which is hard with knife handles, but when turning pens, I think they are pretty safe.