Wait a tick, guys: 1) it happens that anti-radar missiles knock out the AA unit's radar or force it to shut down. In this case, I wouldn't say the AA unit is useless, but its ability to pick out air targets at a distance in adverse weather and to hit it will be severely reduced. Considering an armored SP-SAM or SPAAG, that's what a light ARM warhead will likely do. AFAIK they are more effective against large fixed radars with parabolic antennae, where a hole in the wiring is enough to disrupt the waveform and make the radar blind.
2)HEAT ratings on ARM weapons make no sense. Bear in mind that aircraft cannot use anything other than HE ammo. That's why aircraft guns and rockets have a large HE penetration compared to helo variants. Reducing the HE penetration of ARMs to realistic levels should be feasible, but could be tricky when engaging hardened units like armored SP SAMs.
Hope this clears things a bit.
