I mentioned in the previous post that I do have the Sigma 70 2.8 Macro. Using normal viewfinder AF it is right on the money, on both my t2i and my 5D Mark III. It does make more noise than any other lens I own while focusing, but it locks right on pretty quickly, espcially with the Mark III's improved AF system. It does, however, have problems focusing with Live View on the 5D Mark III, often taking several runs at it before it finally locks on, but occasionally never getting there. If I'm in a position to use Live View (ie, on a tripod), I will often do manual focusing. No problems using Live View on the t2i, other than taking longer than viewfinder AF to lock on, but that's the case for most lenses. The image quality of this lens is so superb, that I can live with the Live View issue. Given the ability to use the 5D Mark III at higher ISO's (allowing higher shutter speeds) I find I am not using Live View and a tripod nearly as much, so most of the time I use this lens now with normal viewfinder AF which works fine. I have taken some landscape shots with this lens and it is as sharp at infinity as it is close focusing on flowers, so it's a good all around lens regardless of subject being photographed. One minor quibble is the hood is a screw-on type, so you can't easily put a lens cap on and off without removing the hood.
