Based on reports from 7i users, noise will be often be visible at A3 size. Why don't you print a couple 7i shots you download from the web at the size you want and see if you like the results? Noise bothers some people and not others. You can try some that have been post processed to reduce noise and some that haven't, if that matters to you.
I've seen zero evidence for the claim that Sony (and Nikon shots) leave less room for manipulation in Photoshop, or that Sony 717 color is less accurate (707 maybe). But since you want a wide angle, that doesn't matter. Just print out some Minolta and Nikon shots and judge for yourself.