i think they removed this quite a while ago and my memory is a little foggy why, but i think they removed spec swapping in wz's to prevent bunker comp's to stall out wz's. i remember before i stopped playing in patch 3, teams would change from heavy dps comps on voidstar offense to almost full tank/heal on voidstar defense making it near impossible to get through the first door. back then there was also the side node speeders on ACW, so when you capped a side node or two you could just spec swap to defense and hold the points with an extra fast respawn path back to the node.