I think kevlar added to armor should boost base DT by 2, just like tabis/balaclavas, in addition to what it already does. As it stands, its imo the weakest of the four cloths by a big margin. If it had no armor penalty I'd probably use it, but 10% for what it does isn't great especially with tacvest extra bullet protection and shields, and it barely does anything on leather.
I think nanocomposite plates should also give some DT, but less than all other armor plates. Psibeetle for instance gives good protection for its penalty, *in addition* to psi cost reduction and psi skill boost.