You guys make EXCELLENT points. And this thread is relevant because I am about to attend a colleague's wedding, and I plan on bringing a camera.
Here's what I do always, and will do shortly:
1) Use the Leica or Mamiya for small, sharp, fast black and white candids.
2) Make small prints, 8x10 at biggest. They almost always beat the work of the main photographer. And, frankly, as a non professional, I am proud of that and love it.
3) I do not step in front of the hired guy, and generally avoid him altogether, so as to not distract or delay.
Is this wrong? Does this make you guys want to shoot me?