I've had luck with some older resin. I found an AMF Ninja RPM - had a few nicks in it, but overall good condition. It works well for spares and is perfect for when the lanes dry out.
I have a Hype Urethane, but haven't drilled it yet, so I can't comment on it.
I'd be a little worried though - sounds like these new urethane balls are fairly strong, and they are coming with even less surface (higher finish numbers).
The older urethane "oil" balls came with much more surface (lower numbers), so maybe finding an older Hammer (red, blue, or black) and taking them up to 800 or higher might be an alternative (they came at 320 grit back in the day).
Heck, you might even look for a newer ball with high games that has suffered "ball death."