The thing you have to keep in mind is that Lock-On does not really have a great track record in PS...ask any Striker user.
Granted, it's most useful against air, but that doesn't mean anything.
I'm also not a big fan of this "BR20 Elite Ability" for countermeasures and a real flight model. Why should that be limited to the BR20 crowd? I understand that they need SOMETHING...but giving them such an insane advantage over the non-BR20s goes against the design goals of PS...that a BR1 with the same weapon stands a roughly equal chance against a BR20. Give them the ability to do things like loops when the BR less than 20 can only do turns, and the BR20 will win every fight, not because they're a better pilot, but because they've been given an insanely unfair advantage.
The way it SHOULD work is that the flight model goes in as a toggle for ALL pilots (VTOL (current) mode and flight mode) and all aircraft get counter-measures (due to the overwhelming AA). The BR20s can get missiles that lock-on for their Reavers (rarer munitions only issued to elite troops or some such), which wouldn't be that unbalancing because the lower than BR20s have some means of survival, but the BR20s still have an edge...just not a massive one.
Sorry to hijack the thread, but the idea of these major changes being only for the high BR characters really bugs me.