It's a little risky to get advise from people who do not know your needs and/or your equipment. But since concert photography is challenging even with 1.4 lenses I would say that you need a 5DMarkIII. Assuming you have FF 1.4 lenses (like 50mm or 35mm).I guess there are too many questions in my post… I'll try to simplify:
1. Apart from screen size/ quality difference, would a MacBook Air work fine for Aperture? or should I go with the (Retina) MacBook Pro?
2. If I should decide to invest my money on a new camera instead, would my late 2007 iMac be up for the task? (with increased file sizes compared to the 10Mpx of my 40D)
TRON: my needs are: portrait, food and indoor locations (as in restaurants) and concert.
my equipment is: 40D, Canon 50mm 1.4, 85mm 1.8, 60mm macro, 17-55mm 2.8 and 55-250mm; Sigma 30mm 1.4 and 10-20mm 4-5.6... so I have a bit of investment in crop.
5Diii would be a dream, but not sure if it's realistic looking at my budget and if it would be overkill for me. I'm an amateur after all…