I'm so mark IVa biased. i think the mark IVa is THE BEST OF ALL OF THE MARKS, having had may different factory c+'s back in the day, i always stayed with the iv and took the money and ran with the c+'s.
with that said, i really do want to own a mark 7 for a minute just to run it through the ringer. the way people describe it, its pretty solid. i've heard NOTHING close to a negative review of the 7. i think they had the pre/power sections on lock down, and it was just a matter of making "ideal" switching work. i mean i loved the mark V, but the IV felt more "organic"/"raw"/"you suck and the amp isn't going to help" but not by much