The problem is that you will probably be drilling back into plug, so you won't get an accurate feel of how this will feel in all your balls.
i am the most finicky person about my thumbholes in the world, and as a result, went to something where i can change thumbholes on a whim at anytime (Griploc!). Anytime I don't like the feel of a thumb (which is what happens about every 3 months for me), bam, i drill up a new one (or 3) and get it perfect. Makes it so much easier than having to plug up equipment, having tape feel different ball to ball, etc. The tape thing is a big issue with me, as i believe you can never place tape the same way twice, and this will always make thumbholes feel different unless you use the same thumbhole for each ball (which you can with griploc).
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stanski