I think one needs to differenciate the weight class light-medium-heavy, and the armor item types cloth-leather-mesh-plate.
The weight class and the impact on the gameplay style are nice in principle… i think the light side need some additional slight advantage, like heavy has the shoulder barge… Maybe something like projectile deflect/reflect (see witcher), or less fall dmg. Otherwise the weight class is fine.
The item types though… I think weight should not be seen as a disadvantage but more like a gameplay decision. In that sense, the light side needs some equivalent advantage, that compensates for the less armour. And since less armour is a massive disadvantage right now, i think it should be a second, different defensive mechanism. The main reason is that the devs would only need to balance two defensive mechanisms, and not have interconnections to other mechanics. And that means… less horrible balancing.
Cloth should also not be exclusively bound to caster types too. Think of a “assassin” with double dagger. This would be a fast, dodgy playstyle with little armour, but not with much magic. And since the armour is a passive element, i dont think that all the evasion to get that working can be done actively by the player to make up for the missing armour.
What i could see working is a passive evasion stat. However (knowing how it works in PoE) a rng based evasion would be a mess in this game (rng oneshot death). It should be something deterministic, what can be actively used by the player. Something that would also go well with the fightstyle we have here. Something like “evade the first hit in 1000/X seconds.” With that one can play much more agressive, however when miscalculated, it can go downhill very quickly.