It is noticeable to many that MAX RT is the weakest and with the most useless ability, in turret mode the rate of fire increases, but the inability to move and the limited viewing radius completely spoils everything. On MAX, in turret mode, it is easier to attach a C4 charge, a sticky grenade, or simply shoot it down with a car, as well as timely destruction of enemy paratroopers becomes impossible. I suggest putting a SHIELD on MAX TR in siege mode that will reduce incoming damage and prevent it from being destroyed with a single C4 charge.
The Lockdown when used correctly or at least before possible nerfs is highly lethal especially with an AA loadout, the C4 threat is real sure but that is where support infantry are supposed to come in and cover your blind spots, up until revives got removed it wasn't as bad of a threat cause medics would have you back in the fight in a few seconds.
No I haven't and I am among those that hopes this change is reverted, but until then your post is mostly true regarding the Lockdown but it's still true that supporting infantry can cover a TR MAX in Lockdown mode from threats such as C4 fairies and if the C4 is not close enough it wont OHK the MAX which many C4 Lights do tend to drop them quite a distance so engineers can easily get the MAX repaired but this is in scenarios where you have competent supporting players or a squad.