S^2
I understand you are wanting to stay away from particle, but if you are talking heavy oil, you are severely limiting your # of choices. I am currently bowling on a 46' sport condition, and EVERYONE else is throwing dull stuff down the ball track hoping their balls has enough on the back to carry the corner. I am the only one who is throwing shiny stuff. I am starting with a High Rev, somewhat mid-laney ball, but it is reading the pattern great! It is reactive and rolling fantastic. Also, what I would recommend more to you is the Big Deal. Although it is particle, it is a light load, giving you a high mass bias, Great length! and very strong backend reaction. Shine the ball a bit just to give it a little glare, not like a marble, and you will certainly love it!!!
--------------------
Chris Heringer