I rarely find it necessary to quote someone and tell them how wrong they are on the forums, but gems like this can't be passed by. This is a prime example of why BHs/Commandos were unjustifiably nerfed last patch (Whiners on the forums).
That shield you're talking about? 2 minute cooldown (that only gives 20% damage reduction, the same as cloak of pain, which has half the cooldown, lasts longer, and reflects damage)
Heavy Armor is about a 5% energy/kinetic damage reduction over medium. I've tested this with multiple characters. 5% damage reduction to half the damage types is hardly imbalancing.
You also mentioned "absorbtion", "roots" and "additional knock backs". What absorption? Please, oh grand master of BHs, tell me what ability I have that puts an absorb shield on me. None? Right. The same can be said for roots. COMMANDOS/BHs HAVE NO ROOT. Just like they have no interrupt. What makes our knockback "additional"? It's our only way to get a melee off of us, period (and it got nerfed too).
I already had good Marauders keeping up with me in warzones. Now they decimate me. They've become completely out of control, with way too much PvP cooldowns/utility. They are by far the more advanced class, in terms of amount of escape mechanics and options for handling situations. Marauders are what all the other advanced classes need to be brought on par with.
Don't try to go pandering to the "I got shot by a BH/Commando" crowd. We do no more damage than Snipers, Marauders, Operatives, Sorcs, and just about every other class with a good player behind the keyboard.