Vermelha - Castile soap bars are still made with lye. The only thing that castile means is that it was mostly (or completely, depending on how traditional the soapmaker is) olive oil and lye. After all, saponification, the reaction to create soap, is the reaction of an ester and a base.

The floating/sinking test seems like a really nice simple one to me. I know mine floats - virgin hair, straight, rarely heat-treated. I do use shampoo bars but I do remember hearing that they rarely work well on processed hair.
I wonder if silicones would temporarily decrease the porosity since it "seals" the cuticle?