Hey Easton,
The Robo is stronger compared to the Delta 1. However, the main difference is their reaction shape. The Rule Delta 1 is designed to go longer and break at the backend, the Robo grabs sooner and is more continuous throughout the lane.
Since they are both asymmetrical, we can control both balls and their reaction shape properties. For a straighter reaction, I'd suggest weakening the mass bias positioning to near the thumb or even under thumb(maybe even left of thumb if your track is not too high currently). Either piece is also very flexible to coverstock adjustments as needed to the amount of oil you encounter. I polished my Delta 1 and it straightened out by a good 8-10 boards so a lite fine tuning can put the ball anywhere in between that easily. Either piece I feel would work for you. Just give us a holler to whichever piece you decide on with your personal info (pap, axis rotation, tilt, speed, revs..etc) and we'll help you out with a layout to get the reaction you want. Thanks....
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Rick Leong - Ten Pins Pro Shop
Track Intl. - Amateur/Pro Shop Staff
Vise Inserts Staff
www.Trackbowling.comSee profile for Track Ball videos
*El Presidente of the Track Legion