After seeing many threads on this stuff here and over at bowlingcommunity.com, I finally broke down and ordered some of the Magic Carpet.

I am so impressed with this product!  If you want a smooth, consistent release and no worries about thumb issues, then I highly recommend you pick up some.

A little background:  my arsenal was all drilled by the same shop, so my thumb holes are all the same.  I struggled this year (my first as a bowler) with gripping the ball.  My coach taught me about using tape to get a snug fit, and I think I fiddle with tape adjustments about as much as Wes Malott!  I also picked up a few "idiot sticks" which insert in the ball and prevent you from bending your thumb.  My game improved dramatically, but I still struggled with my release.

Today I used the Magic Carpet for the first time.  I took anywhere from 3-6 pieces of black tape out of each of my balls and replaced it in every ball with one piece of Magic Carpet and one piece of white tape in the front.

My release was much smoother and I got higher revs as the ball was coming off my thumb consistently at the bottom of the swing.  I had no problem switching balls as the lanes broke down because the fit was the same in each ball.

If you want a smooth release, take a Magic Carpet ride! You can order it here: http://www.bowl4fun.com/magiccarpet/magiccarpet.htm
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Arsenal:
Storm Gravity Shift
Storm T-Road Pearl
Hammer Cherry Vibe
Lane #1 Bullet
Columbia 300 White Dot - Blue Pearl

In regards to tape in the thumbhole, recently I have been referring the following link to many bowlers.  I think it has some really good info on the subject and since it also mentions Magic Carpet, it is on topic for this thread.

http://www.bowl4fun.com/ron/btm04_files/btm4.htm

xiek376 - I know you might want others to chime in, but it's equivalent to 3 pieces of white tape.  I'm constantly fiddling for a good fit so you can trust me.     If you have an old ball you don't use much, it might be a good place to experiment.

Impending Doom - I don't mean necessarily mean (absolute) forward.  Everyone's hand is different.  If you need 3/4" reverse because of flexibility issues then that's what you need.  Too many pro shops automatically put people in a fair amount of reverse.  A lot of bowlers complain about not being able to get out of a ball clean, so they get a lot of reverse and a big thumb hole which just promotes more squeezing.  I just meant if you should have 1/4" reverse but actually have 1/2" reverse you're probably squeezing more than you realize (been there) and the Carpet might irritate your thumb.

Thanks. I would like to try mc. I was wondering if anyone had thoughts on the need to use 3 pieces of tape to avoid suction. I had never heard that and don't currently have room in my thumb hole for it.

Yeah, because a thumbhole can fit TOO good.  Suction can create a manufactured or wrongly identified "sticking."  I have the IT, and have put a vent hole at the bottom of the slug in the vent slit to prevent creating the vacuum in the thumb. 

Thanks. I would like to try mc. I was wondering if anyone had thoughts on the need to use 3 pieces of tape to avoid suction. I had never heard that and don't currently have room in my thumb hole for it.