Upgraded my Leica M4 to the FM3a. Did a test with M6, Bessa R2 and the Fm3a what do I say, simply magnificent camera, good handling fast shutter speed (1/4000, pretty important for me shooting 200 asa all the time), the noise ??? so what I personally am not nothered by that, and those who are ... who cares. It's not that the noise of a camera makes one conspicuous or not....
Shoot with a so calles silent leica and peole will go "ahhh a leica" etc. etc. I have the FM3 alongside my Hassleblad 503 and I must say they are an excellent couple. I use the 50 1.4 which stopped down to 2 is a most remarkable lens. I only shoot TRI-x 400 at 200 with it which I always develop in D-76, the images we bring to life are simply great. The FM3 is a camera for life I guess, and I would never think of getting rid of it ... I would say go for it.
And since you do weddings get a nikon flash with it... works like a dream.