Hey, just chiming in on my 2 cents.
The Aura is fair. This is a unique, team lead sort of unit.
Then wouldn't it be more fair if the team lead did not receive the buff, like it does currently? I think that's a fantastic fix for the command p4.
P4 command tank gives 20% damage reduction to units in the aura.
Essentially, units have 120% HP. It's nice if you have nothing heavier than a Panther to take on an IS2, for example.
I read about this somewhere a few months ago on these very forums that rang true with me. It may be 120% hp, but think about the time to kill a tank that is affected by the command aura. If a standard p4 has 640 hp, and with the command aura that hp becomes 640 + 128 = 768, then the shots it takes to kill that p4 goes from 4 --> 5. That means the unit's effective hp is 125% because it takes 25% more time to kill the unit with the aura than without it. The buff is stronger than just the stats.
Like I said, I'd be in favor of removing the buff on the command p4 only. It makes "focusing the leader" viable, whereas right now, not so much.