I just tried mine yesterday during leagues. Drilled 4x2.5 from my PAP (5 X 1/2 up)Pin under the ring finger, MB on my VAL. Drilled the same as my RULE and 5.0 (drilled 4.5 X 3 pin in middle under the fingers MB on VAL).
Brunswick synthetic lanes freshly oiled with medium carry down with an out of bounds past the 5 board.
The Delta seemed to rev up a little later and harder than my RULE and was stronger on the backend with more continuation through the pocket for me. Very easy to read and forgiving, took well to different hand positions also.
Delta compared to my 5.0 was earlier with the same backend move as the 5.0. But the Delta handled the carry down or spotty backends better and was more forgiving. The Delta has the same Great HIT as the rest of my Track balls.
Got this Delta 1 early, thanks to William Clark at the Bowlers ER in Des Plaines.
Hope this helps you out a bit.