The fact that vehicles can reverse with no penalty make turning radii completely nearly moot. Especially for walkers, there should be some sort of penalty.
Non-vehicular models may turn as many times as deemed necessary for no MV penalty. Effectively, this gives these models the manueverability that a foot soldier deserves.
Vehicles are limited to one turn per AC. I have seen this abused. I have seen models moved "sideways" (side-step, etc.). This is illegal.
There should be a limiting factor for reversing. Half MV seems fair, to me. This would limit the Richard-dancing, and make those who would bring vehicles onto the board be more tactful with them. As it stands, now, vehicles are not (from my experience) held to their limits.
If an EDD had to turn 180° in order to move back out of LOS, this would make the player have to play it more carefully. Instead, the player moves the EDD forward, maybe having to change facing a little to get within the arc of fire for its weapon, fire three times, then walk backwards just as fast as if it were moving forward, never exposing its rear facing.
I may be spouting out some of my own frustrations, but, does this sound right to anyone else? I do use vehicles (like the strike skimmer) and have always tried to manuever it within the rules, and have taken advantage of the same rules with which I am in disagreement. I would, still, like to see some type of reverse MV penalty.