Back when the Zone Classic was actually new, I was watching a reputable bowler with one that had the typical Zone linear pin/cg/bias lineup.

He had the mass bias almost into the bridge, I can remember if the pin was drilled out by the thumb/under thumb or if it was placed a touch outside.

I didnt notice any odd ball reaction out of it.

Any thoughts or ideas?

I forgot to mention, he wasn't a full roller. Had some decent tilt on the ball too.

I once had a Nitro R2 w/ the pin about an inch to the right (away from track) of the thumb, CG above (3" pin).  Rolled like it was negative weighted.  I used it mostly when I needed to play deeper, but I could also play the ditch with it on the right  conditions (Silver lanes in Spokane, if anyone remembers).  Didn't over react, hit hard.
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"I do desire that we may be better strangers."  Willie the Shake, As You Like it(III,ii)
"I'm capable of being just as sorry as you are, Dimitri."

I just experimented on a Whirlwind (based on a more knowledgable person than I) by placing a 4" pin under my thumb and CG in the center of my grip. The ball is fantastic, it goes long and smooth, and has a nice arc into the pocket. It's the most consistent move I've seen from a ball compared to other tame drillings in lightbulbs I've had. Although I was extremely worried, it doesn't clip the thumb at all (nor does the person who showed me this drilling clip his).

I should one other driller/bowler how it reacted, and he promptly drilled a 2" pin version in a Uranium HRG for himself. It does clip the thumb very late on the lane, but I think we can easily counteract that with a well place balance hole -- of course this is beyond my abilities at the moment.

We are all your basic semirollers, myself being inverted.