I used the free weekend to check what would transfer between platforms if I chose to play Evolve on another system. I play on PS4 and during the free weekend I installed Evolve on PC and linked it to my2k account (the same one I use on PS4). Unfortunately the only things that got transferred were the skins awarded for community challenges. In my opinion it would be great if all of your ingame progres was stored at your my2k account. And I really mean all of it including not only characters elite status but also achievements and ingame accolades. That way you would keep your progress regardless of which system you would be playing on.
Obviously that paid content would not transfer.
Now if you ask why it should be so I can only give you two reasons. One is that I have friends who do not want to get PS4 but would like to play Evolve and since I put so much time into this game I do not want to start from scratch. Another is the Xbox Elite pad which really appeals to me and would like to play this game with it.
Oh, a third reason just came to my mind. I would be paying TRS again for the same stuff that I already bought on PS4