I just put the Grovers in (406C are the ones you want) and I dig them, I don't think there's any other drop-in replacements because of the screw hole location.
Grab yourself a PRS USA nut while you're at it, great inexpensive mod, plus you get to say "unobtanium".
Tremol-nos are great for what they do but they won't improve trem stability at all (the nut will).