Re: Finger tips or flat-fingered? Are both equally good?
Maybe the build of your hand plays a role, too.
I think I bend all my fingers, except my pinky, which is shorter than the rest, and curved to the inside (a handicap known as "clinodactyly")
IMO with both techniques you can play fast enough for Cajun music, which is generally slower than Irish trad or Canadian reels. Maybe that explains why both techniques can work for Cajun music.
Anyway: You can move your fingers as "fast" as you want, but don't forget the bellow, which has to follow suit as well! If your left/right coordination isn't right, it doesn't sound right, whether slow or fast.