One note about the Frantic and Storm's "1500 grit polished" finish: The polish they use is so abrasive that even though they start with 1500 grit when they apply the polish, by the time they're finished the actual grit level "under" the polish is actually in the 3000 - 4000 grit range. So you just refinished the ball with the same surface, more or less. So, it's not surprising you saw little difference.
To reduce the backend what you need is less surface. The current suggestion on the table, to sand it to 4000 grit, is a safe one. That should allow it to handle the same amount of oil, but it will grab the lane slightly earlier, have slight less backend, for more control, and handle carrydown slightly better.
Another choice is to use a much rougher grit level under the polish, like P1000 or P1500 grit and then apply a light coat of polish with a mild or non abrasive polish or even do it by hand. Valentino's Snake Oil is a great non-abrasive polish.
Not sure whose "Factory Finish" polish you have. There are several around and they can vary wildly in how abrasive they are. Ebonite's/Powerhouse is a good Factory finish polish and is less abrasive than Brunswick's Factory Finish which is fairly abrasive in my experience.
