The way I see zeus vs. maverick is this: mavericks are for anti-unit. They have reasonable speed (compared with the units they'd often be attacking), a fast-moving weapon for attacking units that are faster than them, decent enough range and huge damage per shot to obliterate any enemy skirmishers before they can get close enough to do any real damage... etc. They're ideal. They're a unit highly representive of Arm. They can't take very much of a beating, but they only need a few moments to be back at top performance.
Zeus are more like the Arm's enforcers. Arm knows that they can't always have the high ground, better recon, and the opportunity for better planning, so here lies the necessity for a unit like the Zeus. The way I see this unit being developed is in the realization that Arm will have to play dirty every now and then. The Zeus was designed as being the closest to the Core philosiphy as Arm has ever been. It has great firepower and incredibly high HP for its cost, while still remaining somewhat more mobile and than its Core counterpart, the Can. Zeus are best used in large numbers in a wide formation - you can't stop 'em all, and when a couple of them finally do get within range, they'll make you hurt.
Yes, all things being equal, you'd want Mavericks over Zeus any day. But all things aren't equal, and Mavericks are really expensive (in more ways than one) in comparison and don't have the battlefield longevity to survive long enough to actually attack a base's defenses and come out on top when cost to both sides has been considered. In order to be economically feasible, a Maverick must survive several battles in order to be worth building - they are not "throw away" units like Pyros, Cans, Zeus, Hammers, etc. In an evenly-matched game, you cannot use Mavericks in an assault role - every single one lost is like losing a half dozen lesser units, and against the firepower of HLTs, plasma batteries, etc, they can't last.
Gotta get that new hard drive soon
