Have you seen the presumed Devil Walker fight arena? Almost no cover, close quarters, and two at once. It is going to be difficult as -blam!- to manage that if vandals and shanks start popping up. If the Walkers move to opposite sides of the map the crossfire would be ridiculous, and any attempt to move towards the edges would be hampered by their AoE shock melee which has a very large area for an attack of that type. Their main cannon won't be much of a threat, but the carriage gatling and rocket launcher will devastate. Add in the fact they will likely have a major buff to health over normal Walkers, and this will become a fight where it would actually behoove you to focus on destroying the rockets before moving onto the legs.