Age-old debate: EF 24-70mm f/2.8 L USM or EF 24-105mm f/4 L IS USM

OK, I'll add myself to the list of hand-wringers...

I'm looking at the 24-70 and 24-105 as a replacement for my 28-135 IS. One of the reasons I'm looking is just for better IQ in general, but specifically for a good lens for indoor shooting, events, etc.Right now I'm learning the challenges of photographing my daughter, a fast moving toddler, primarily indoors.

Intuitively, it would seem that the 24-70 wins with the extra stop of aperture, but I've found that in available-light conditions I still need to crank up the ISO at f/2.8, which gives me results I'm not all that happy with in terms of noise, color definition, etc. It's also a very heavy lens.

The 24-105 is lighter, has more reach (something I like for candids/portraits and the outdoor action), has IS, and overall seems to have equivalent image quality. The only downside I can see is that I'll be using my Speedlite 430EX II more often with the 24-105, but maybe that's not such a horrible thing anyway. The IS is also a plus because it would likely yield a better image in the hands of my not-so-photographically-inclined wife and other family members.

So despite the fact that I'd love to have the extra f-stop for low light, I find myself being drawn to the 24-105.

I'm guessing the replies will be split down the middle, as is this poll and every other discussion, but I figured what the hey--we'll see what you guys think. :)