So far so good without using inserts. No middle finger pain, slight irritation from the extra friction, but only because I've never gone without inserts.
Only thing I did notice was a little bit of swelling/stiffness in the ring after bowling (bowled like 10-15 games), but I have a feeling I need a little more bevel there.
One thing I could not do was pull shots, I just couldn't do it. Didn't mean I didn't miss to the right some shots, just couldn't pull it in of target.
I did this on my Toxic, was lefty now righty (just plugged the finger and re-slugged the thumb) and my first pin under drilling too. Pin is about an inch down and next to the ring. Great ball roll!
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"Trying is the first step towards failure" - Homer Simpson