Does anyone use that zoom lens ? I mostly use my two dslr bodies (40D and recently acquired 70d) for wildlife photography but i need an all around zoom mostly for portraits, landscapes and travels.

I know the 24-105 f/4 L IS is certainly my best option, but considering the low price of that Sigma lens, i'm curious to read opinions from photographers who utilize or can compare it to the 24-105 f/4 L IS or even the ol' 24-70 f/2.8 L (if it can be compared to these kind of lenses)...

I f you're fans of other third party zoom lenses that can interest me, don't hesitate !

Thanks.