I was thinking to armenian all this, night how in my ears it really sounds so much like indo-iranian, and semitic, also indo-iranian sound something very " south ". I remember have listen a whole hittite text, and i had exactly the same feeling, with a lot of french R instead of rolling R like many indo-european even indo-iranian languages. Maybe, its not about the whole yamna culture, or R1b / R1a... And if, yamna was, dependent by two cultural center, one in the west Dereivka and one in the south-east, Maykop. Maybe that those two culture, are the source of Centum language for Dereivka and Satem language for Maykop. Maybe the R1b / R1a - Centum / Satem split is take the problem upside down. Maybe the relation with people and linguistic is more complicated that it can be.