I know of one guy who has them, but he put them in a used ball. His span was a little bit shorter than whoever had it drilled, so instead of plugging, he popped in some finger slugs and drilled them out to his span. I asked him about it once, and he says he doesn't really notice much difference compared to his other stuff that doesn't have slugs or insterts. That's on the fingers though, he won't throw without a thumb slug.
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9~
Keep your balls on the lane and your mind in the gutter!
