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If you are using the Electronic Shutter Scene Mode, the camera is completely silent. I mean no noise at all! The only limitation of the ES mode is that it only works on manual exposure mode and it gives you a simulated match-needle to get the exposure right. Ricoh doesn't recommend shooting action with the ES mode, but I've heard some reports that this works just fine. While it won't serve every situation, for those times when stealth or subtlety is of the utmost importance, this is pretty cool, and just isn't something the M9 can do.
I've never heard an M9 before so I can't compare the shutter noises. The regular shutter on the GXR sounds quieter than the E-P1, though it could be that the E-P1 is just a high-pitch. The GXR is quieter than the R-D1.
I think the lack of AF will improve battery life. Unless one uses an external optical viewfinder, the EVF or LCD is on pretty much all the time either way.
As for shooting off the back LCD, I don't think of it as "like a point and shoot" since up until recently most P&S cameras didn't have such a thing. I think of it as "like shooting off a focusing screen on a [twin lens reflex or crown graphic, large format camera, etc]. It works quite well, I can't see not doing it because of what it might connote. Unless of course you're in full sunlight.