Thanks for your help, I saw the cashback offer which is making it very tempting indeed! They both got similar reviews in a mag I was reading last night (can't remember which one) ah decisions, decisions! :)
Sorry to jump in on your converstion and completly change the subject...I am looking at buying the sigma 50-500mm or the sigma 150-500mm does anyone here use them on their 70d for wildlife? Which one would you recommend or would you recommend a completly different lens? Thanks in advance.