Lots of empty space in there, so many penetrations will do relatively little.
With regard to reaction, my HT's get the wind up and back away big time when they come under ATR fire.
My opponents and I don't use any vehicle crew motivation higher than normal though, as we all agree that the higher level crews don't behave like real human beings.
If your crews are highly motivated, they may not do much in the face of ATR fire, being supermen and all.