The AI selects it's gear by looking at the gear table and drawing a random item from it. There was no evaluation of how good sth. is in the first place, so these changes shouldn't make this worse.

Eh? Well, yes, we decide that then. That's our decision. Someone else might come to a different decision. I don't really understand why you want Spectra to unambiguously win over Guardian. The point is to change this so this does not happen anymore.
We now have a clearly defined progress with Kevlar -> Twaron -> Spectra. Protection and coverage gets better, penalties worse. The rest being variants or extreme outliers (EOD, Kevlar Leather). But no armour should be obsolete in every way (price is not a good counter for this - most armour comes from enemy drops anyway, so buying price is irrelevant).

I think you misunderstood silversurfer here. The AI is subject to all penalties. It just doesn't care. There is no decision process involved. Some factors, like weight, price and stealth though are irrelevant.