right now i have a 24-105 f4 L lens that came in my kit. i breifly owned a tamron 28-75 f2.8 which was awsome on my old 30d. now im debating on selling my 24-105 to rebuy the tamron 28-75. on top of buying a lens with a wider aperture, i would have extra cash for a flash. then i started to consider the sigma 24-70 f2.8 for a few dollars more. ive been looking at reviews and i have confused myself. anyone buy one of these lenses that shoots full frame? which lens did you get and how are your results?