Hi All, I've been looking to upgrade to full-frame, but I'm working on a budget here. I'm starting to work professionally as a photographer, but I'm having trouble 1) labeling myself as a professional when I'm shooting with a prosumer Rebel and 2) the AF limitations of the t4i. I can't always quite get the shot with it. So, I'm looking to upgrade to either the mkii or mkiii. I've found some secondhand mkii's in the $900-$1000 range with reasonably <20,000 actuations. Would a brand new mkiii be worth $1400 more than the mkii in terms of autofocus and quality? I have enough cash saved up for the mkii, but would it be better to save a few more bucks for the mkiii? Thoughts? Thanks in advance!