[Mobhack]

In your original post, you were firing at planes with only 1 EW level below the SAM's. EW level is a major factor, if one side has a signifigant differential - and 1 level of EW different aint so. If the SAM has maybe 3 levels of difference or more it will do much better (or conversly the other way if the plane has the higher differential).

Area SAM ae a useful thing to engage stand-off planes, less so against planes that come in over the map and helicopters. So for myself, I tend to invest in ZSU systems, or short range missiles like Rapier. SPAAA gun-based systems can also contribute to the land battle if necessary, whereas SAM (other than the Canadian ADATS) cannot.

As to the aircraft armour changes, that was changed a few releases ago. Check the release notes (found in the game guide) for details. Specifically, bullet point 26 of release 12.