Same feeling from ball to ball.
Also - a way to move/resize a thumbhole quickly, if the span is close.
But mainly feel. I use exclusively urethane slugs. I mistakenly bought a few vinyl ones, and had them put into a couple of balls. OOPS. That was a big mistake.
NOW - slugs are different than the inserts. Inserts are presized, pre drilled. Slugs are drilled at the same time as the rest of the ball. I DON'T like inserts. They are awful - in my opinion.
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Bowlers are like puppies. The only difference is that someday the puppy will quit whining.
-- Found at Sam's Town Pro Shop