Hi, Yes I agree, the Canon 300 f2.8L is definitely a nice lens. I had a Canon 500mm f4L and after one outing with it I I realised it was too heavy for me to carry around. I sold it with the intention of getting a 300 f2.8L but when I saw the Sigma lens I thought it would be more versatile, unfortunately I didn't realise the Sigma build quality and QC wasn't up to Canon's standard. I'll send it back next week and hope it comes back working how it should have done out the box. That will teach me to try and save some money.
Thanks for your reply's. Much appreciated.