very few hints of something about them
but my story for my warband cult is that we are one of the fleets that DIDN'T go blood raven so we bare the original armour while changed to resemble post TS.

I did not say that's not possible but think about this the flesh change was happening to all TS in the warp, I also fell Magnus sent those others out looking for a cure.

which is what i based my cult story on

Has to do something with Revuel arvida saying knowledge is power http://warhammer40k.wikia.com/wiki/Revuel_Arvida

well the mentor legion also sais knowlege is power and they are 1 edition spacemarines

i think you are thinking of the minotaurs not the mentor

I will be at your side brother

well no problem bannus. And i say you are right about the Minotaurs, atleast if left over sons are blood ravens then minotaurs are left over worldeater gene-seed

Consider me enlisted into your ranks

Another one shall fall by my claws then