I guess its too late to change your mind, but the 24-120 has reports of softness, and its got a small max aperture, and a huge change in aperture from 24-120. You'll have some serious speed issues shooting weddings with your lens. If your aperture is f/5.6 in a church with no flash, VR or not your shutter speed is going to be abysmally slow. VR might not help enough, because even on pro lenses you can get steady shots at between 1/15 or 1/4 of a second, but shooting f/5.6 in a dark church, even with your iso cranked up its gonna be slow. ESPECIALLY if you tend to use the long end of your lens.Originally Posted by jokola
AND MAY I REMIND YOU
that VR does NOTHING for subject motion. In your 1/2 second, 1 second etc. exposures, depending on conditions, you'll have lots of subject motion.
If you do crank up the ISO you'll probably have lots of dark areas that will catch a lot of noise.
If I were you shooting weddings handheld without flash, I'd get a fast lens. and I mean fast. like f/2 or faster, and shoot with ISO cranked up, then pp with one of the aftermarket noise reduction programs.
There are a few interesting lenses out there that might serve you much better, like a 50mm or 85mm f/1.8 or 1.4, or even the 105mm f/2 DC, which will allow you to take control over your out of focus elements.
Finally make sure you have a LOT of memory cardsYou'll likely have just as many botched shots in low light as I do.