ATG guns are a B!+ch. I find them much harder to handle than an enemy tank (Wittman said something along those lines, I beieve). With a tank you can see when you've K.O.d it. With an ATG you can pound the area with HE and think nothing can survive it - but unless you see the K.O.d ATG you never really know. As said, one poor survivor can man that gun to amazing effect, and the ROF doesn't seem to be negatively impacted very much.
I have to pull back and remind myself that this is a game/simulation. A few rough edges where things seem 'off' don't matter much. I use more HE now than perhaps a real-life battle would take. That ATG gun will be knocked out, scattered to scrap and there will be nothing resembling a human form left of the crew before I get done with it. I keep suppressing fire on the position unless or until I see that dead gun!