I only use them in L perms (R' U L' U2 R U' R' U2 R L), and I do them as R r, with the r being done with my left little finger. But given the choice, I'll avoid them.
I don't know? I've never had any problems with that fingertrick...
Because it looks like an L and not like a J At least other people use J/L instead of Ja/Jb; I'm not calling Ra perms Q perms... (but I do actually call Ra perms 'Q perms' in my head, but I don't say it because nobody would understand me)
sorry if my drawings in paint aren't very good, but: q perm!