I'm gonna buy Sigma stock. Nice to see a company not coming out with completely unnecessary lenses...*cough* 24-70 f/4 *cough*
24-70 f/4 IS = better than 24-105, has IS, costs less than f/2.8 II = not so crazy?
As for this Sigma, it sounds cool, but I'm sure it will be a bit of a beast and I don't anticipate selling a 24-70 2.8 II or f/4 IS for such a lens myself. It's interesting though.