I haven't shot with a 5D, but I have 20D, 1DM2, and 1DM2Ns. I would say the 20D is louder than the 1DM2 and 1DM2Ns, but I also wouldn't say the 1 series shutter is quiet. It is noticably less, but still not quiet. I would guess that the 5D is about the same, as I haven't heard or read to much about it being an issue one way or the other. The 20D has long been known to have a loud shutter. By the way, it isn't the "shutter" that is making the noise, it is the mirror slapping.

As for the 5D vs. the 1DM2. You have chosen two extremely different genres of photography to use the same camera for. Obviously either will do the other to some degree, but is not the best at it. The 1DM2 is going to be faster and much more ruggedly built. The 5D is going to have an edge at high ISO shooting, and is a lot lighter (think about a day of wedding shooting... do you want the extra weight of the 1 series build?). I know that there are people shooting the 5D for sports and happy, but it isn't the camera of choice. I would say the same goes for the reverse. Prior to the 5D, a lot of shooters did use the 1Ds and 1DsM2 for weddings. I honestly don't think you could go wrong with either one.

__________________
Mike - Been Converged?