I've been doing it for 10 years (standard fingers, just no thumb). Average between 200-210 bowling 3 games per week, no practice. Throw a straight ball with thumb for right-side spares, but everything else is thumbless.
Advantages for me (YMMV):
- No more lumpy thumb
- No more sore finger knuckles
- No more wrist problems
- Haven't had a blister in 10 years
- Much more power
- A clean release every time
- Cheaper balls work the best for me because I don't need the big hookers
- Wet lanes are much easier
Negatives:
- More splits and weird leaves
- Dry lanes are tougher
There are a lot of false assumptions in this thread. I can get the ball up as high in the backswing as my lower back. I have plenty of speed when I want it. I can hook as much as I want or throw it fairly straight. I have very good control on the strike ball, but it's the "thumb in" right side spares that are costing me 10+ pins on my average. Especially the darn 10-pin.
In fact, most people don't even realize that I don't have my thumb in the ball. I've bowled in a league with people for years who haven't realized I don't use my thumb. I don't palm it. I only cup it enough to keep it in my hand. My hand is only average size. I don't have the severely inverted roll that "palmers" do. My track is very normal, about an inch from the holes. Personally I think my ball reaction is similar to the old pro John Gant. Which is great because that's who I modeled my reaction and delivery after, although I made the switch after watching Mike Miller. I had just gotten fed up with leaving 10-pins all the time. Now I leave 9-pins instead but it looks better
.