Which EPA-100 bearings?

I picked up a nice EPA-100 a few months ago in excellent cosmetic and functional condition. The bearings seem good, as far as I can tell—it passes the WallySkater stiction test with aplomb, anyway. And it sounds remarkably alive and resolving with no obvious behavioral issues.

Still, given the famous fragility of its ruby bearings and the age of its internal wiring, I suspect it can sound even better with some refurbishment—new bearings, new wiring, whatever it needs. I think this tonearm is good enough to warranty the investment. 

JP at Fidelis Analog has graciously agreed to work on it. He offers, and prefers, silicon nitride ceramic bearings (Si3N4) for both performance and longevity. He also has a supply of ruby bearings for those who prefer to keep it original. So, I have a decision to make. I like the idea of keeping it stock but I want the best performance and, most important, sound.

Has anyone compared the sound of Si3N4 bearings to the original ruby? Has anyone replaced the ruby with Si3N4 and regretted it?  I’d like to hear some hands-on, ears-on experience before I make the choice.

Thanks!