M1 series is in fact an example of "shot traps" with it's huge gape between hull and turret required because of high motor-transmission compartments (to provide turret rotation).
Do You ever in Your life saw how it is designed? There is no turret race ring there, it is placed lower behind hull protecting collar, while the upper part of this gap is in fact lower part of turret front armor. It is a weak zone yes, but not so drastic as some belive.
Anyway what is the probability these weak spots on the T-90 would be targeted over the more reinforced points in a tank battle? Sure a missile can, but they are a lot easier to defend against than an APFSDS round.
That place is very unlikely to hit as it is representing a very small surface, in any tank. I seen many tanks that were hit ina battle, and never I seen for example M1 hit there by APFSDS, HEAT, RPG or ATGM.
Soviet design of 3 man crews
It is not Soviet design, west was also experimenting with 3 crew members designs. Well to be honest Americans were experimenting with autoloaders in WWII period on T20 prototype series of Medium Tanks, Germans also were experimenting on autoloaders or similiar devices, however with smaller success than Americans.
while providing the same level of protection as a NATO MBT.
Frontal protection of both designing schools is similiar, side protection of western designs turrets is better in basic configuration, comparabale to eastern configuration if it have implemented ERA package, but still, also western design can have side turret reinforced by ERA or addon composite, that will provide with basic composite armor probably much higher protection levels than the opposite design.
It does not mean that one designing school is fundamentally better than another, they are just different.
