Although it's most likely common knowledge by now, the slighltly not as cool looking version of this set https://vanillawowdb.com/?itemset=492"">(Item Set #492) are also not eligible for transmogrification.

I will add that while I was rather disappointed when i discovered that none of this awesome looking gear can be mogged, I do suppose that it is nice that Blizz does something special for the people who have been playing since vanilla so that when other people see a toon that has lvl 60 PvP gear mogged those people know that they are not worthy of being in his/her presence because that person is a WoW PvP veteran and got his/her achievements when achievements actually meant something.