the macro version is the new version, according to sigma its completely new optics, which are supposed to be better than the already very good older version.
Im ordering mine tomorrow, so i will let you know! Decided to go with the 70-200 with a TC, i dont think i would use the 100-300 with a 1.4 as much as i would use the 70-200 witha 2x tc, the 70 - 100 area i dont have another lens for so it might well get used for that, and with the 1mtr minimum forusing distance, i dont think i will do wrong with that.
Looked at the 100-400 canon but i cant justify the cost