I am also looking into the Maxis. So far, I've gotten two interesting reviews:
From a toolhouse: "Greenlee used to sell it (TRUE), but dropped it because there were problems- but it might work for light duty"
From the parts house: "We sell them...about half the buyres love them, the others bring them back for refund (no problem)"
I suppose if your main desire is to let one guy pull mutliple #12's, in longer runs... or for smaller feeder runs (2/0 and smaller), the Maxis will probably work out.
For the long runs of 500MCM, you'll probably kill your hole-hawg.