Well like I said, on Bamyan Std, the helis are basically rendered useless after you reach a certain point in the map UNLESS the A10s kill the BMPs at pretty much their spawn points or just allow them to destroy the helis until they reach a point at which the A10s can kill them within the normal rules. BMPs are basically in par with AA other than the range at which they kill you, which in a place of no cover around you is still pretty far. There are a few maps that are kind of like this, where a BMP can kill you from around 2-3 flags away because of the open nature of the map and where the flags are located. I will say I am not defending baserape - I think baserape ruins the fun for others, especially when the CAS kills all assets way before they even get within shooting distance of infantry. I do however think their should be some exceptions for some layers/maps.
Also another point to bring up (using Bamyan as an example again), baserape as far as I understand it is based off of the amount of flags you attack the enemy ahead of the current attack flag(s). Where I think this can be kind of confusing is like on Bamyan - once into the the second half of the map where you really start to see the assets coming in, what can be classed as baserape per flags ahead? I ask this because the flags are so close, and by close I mean just a few buildings down. So would killing a BMP 2 flags ahead, a.k.a, just a few meters ahead, still be classed as baserape? If this is a bit confusing to read I understand so feel free to ask, I can clarify if needed.