I drilled up a 505A recently. 

 

70 x 3 1/4 x 25

P2 Hole, large/shallow

 

I picked up the 505A after liking the 715T very much.  My 715 has a 75 x 3 x 55 layout.  It gives me a nice midlane with good continuation.  It isn't overly aggressive nor overly weak, just a nice benchmark ball.  On a recommendation from Mo, I put the 70 x 3 1/4 x 25 on the 505. 

 

This layout makes the ball very straight with a good move on the backend.  With my moderate axis rotation, this isn't a ball I can swing very much.  The quick read of the friction makes this ball that hook and then sets.  The carry was exceptional provided I was playing them pretty straight.  My first set out with the ball was 740 at a house I've bowled at about 4 times in the last 5 years. 

 

I think this ball, with this layout will be a real winner on the right condition.  However, it will be condition specific I'm afraid.