You're going to have to wait for widespread adoption before you can get any picture of that.
I can tell you this much: I have a RM650, and it is not immune to coil whine. If I put a whining card on it, it will echo that card's whine at half the volume. However, with cards that have no whine, the RM emits no notable whine of it's own (tested various GPU and CPU loads) - this is more than can be said about 4/5 of my more expensive Seasonic X units.
I'm eager to see more user feedback.
Edited by Oubadah - 11/13/13 at 10:32pm