I use the VISE IT in all my balls and it works great. I decided on the 'IT' system because I had heard about Switchgrip breaking a lot, but it appears as if they've re-designed the system, and no longer have any issues. Not only can I keep my thumb feeling consistent across all my balls, I have the ability to switch to a tighter/looser thumb depending on shrinking/swelling. As well as a summer/winter thumb. Ever show up for a tournament to a place that doesn't have AC? Good luck getting out of the ball clean, and you'll be SOL when every single thumb is the exact same, and you can't fit in ANY of your balls. With the IT system tape is no longer an issue, as I can swap them before the rack is reset for my second ball.
Another good thing about these thumb systems, is when you go to Pro shops that have the "Try before you buy" system. You can take your own thumb down, put it in the 3-4 different balls they have and get a more accurate read on the basic layouts they use.
Plus if you buy used balls here and there, you're more likely to find one with a changeable thumb, so that you can throw it without re-drilling it. Then based on current reaction decide how you want it re-drilled for yourself.
Another plus is, anyone you know well enough who also uses the system, say you see them buy the brand new <any ball name here> and you've been thinking about buying one, but weren't sure how it would roll for you. Throw your thumb in your friend, teammate, pro shop driller, 's ball and try it for yourself. You can get away with 1/4 short to 3/8 long span, and still get a general feel for how the ball rolls. A lot more feel than buying it off the shelf blind.
There are many positive aspects to these thumb systems. A lot more than just consistent feeling from ball to ball.
