If you have t2 metalextractors and want to build t1 units, you need ca. 100 t1 factories and a huge area under controle. I think, a t2 factory should have a lower roll out time or they should produce multiple t1 units at once. A t2 vehicle factory producing 4 or 6 ants would be realy cool
Depends whether you see them as Advanced "Vehicle Factory", or "Advanced Vehicle" Factory. You see them as the former, but they've been implemented as the latter (i.e. a Factory that builds Advanced Vehicles, not some kind of super-factory).
I dont think that t1 is obsolete. The Problem i see, is that i cant invest 400 metal / second in t1 units to get an army, large enough, to overwhelm t2 forces.
Boosting the output of a T2-structure seems a strange way of to solve this problem, wouldn't you say? Why not cut down T2-forces in power instead? Fighting fire with fire is not the best way to balance things.
Solution to that would be to make T2 units slightly less cost efficient than T1. So building additional T1 factories would still remain a valid approach. But the way it is, not only T2 units, but also T2 factory is much better than the T1 counterparts - in every single dimension .