Well, after adjusting some material properties and fine-tuning a few settings, I got the render time on my quad-core rig down to under 6 minutes per frame. I can even do it with motion blur at less than 8 minutes per, but I'm foregoing that for the test animation. My dual-core system is considerably less powerful, taking upwards of 15 minutes per frame, but it still helps quite a bit in the long run. The third single-core system is out of loop at this point as it only has 32-bit WinXP and won't work with the 64-bit systems through Backburner.
I re-started the full 300-frame animation from scratch about 9 AM this morning and it's well over half way to completion. If all goes well, I should have a finished version ready to post by morning.