MAX jump.

[Kriegson]

As someone else mentioned, a mechanic where, for instance; Hold the jump button down to pressurize the leg pneumatics, release to jump. While charging the pneumatics you cannot fire, though MAX's can jump a fair distance (not height).
Sort of a "leap" to allow them to dodge some AV or vehicles ramming if use skillfully, and to keep them unpredictable when players are fighting them (If you know it's simply going to trudge around, its easy to kite. If it sometimes leaps forwards varying distances, it becomes a lot harder to fight).

Perhaps there could even be a point in certing overdrive where you could transition from a fully charged leap into an overdrive sprint!