RE: BEC low battery cutoff
LVC is set by the esc not the rx or tx. So it should be just like before.
And NEVER NEVER EVER turn off the tx with the plane still powered up!!!
It's ALWAYS tx on first, plane powered up second, followed by plane unplugged first, then tx turned off.
Turning off the tx first can allow the rx to pick up any kind of stray signal and fire up the plane. Can get real ugly real fast.