Well now that everyone has thrown their "You wont be good on tough shots thoughts" and "Pro bowler blah blah blah".......
I have been bowling exclusively without my thumb for 11 years. When bowling well (which right now I am not---admittedly), I can be as accurate as anyone. Ive had success on tougher patterns---Nationals and PBA patterns.
The most true thing I have seen mentioned in this thread is how long it will take to master. The more revs, less accuracy notion is not true all the time. It is true most of the time. But there are some people who are more accurate without their thumb-------Im one of them.
All that said, if you have established your game with your thumb in, I wouldnt switch to throwing without your thumb. Your timing will inevitably change. You may need to redrill all of your equipment to get it to do what it is supposed to---when I bowled thumb in, I spun the ball, then when I throw without my thumb, my track inverts. It gives you options if you are going to switch back and forth. Problem with that---some people dont know what to do with their options or when to throw thumb in or thumb out.
My suggestion.......
Do what you enjoy.
Stick to 1 or the other.
If you throw without your thumb, turn your ears off. Youll hear garbage all the time about sticking your thumb in the ball, blah blah blah.
I have alot of opinions about this, but theyve been expressed over the years. What it comes down to is why are you doing it? If you are doing it purely for more power, you may not realize that missing the head pin 1 or 2 more times a game or leaving more greek churches basically eliminates any carry advantage you have from throwing NOTHUMB.
Just my 2 cents.
--------------------
Only Losers Feel Pressure
www.thetimekillers.com