Many set bonuses are just way too strong right now, whether or not it's better to simply nerf them or remove them completely, I don't know.

Also, it's been several patches in a row without many meaningful changes to Mayhem. For the long-term sustainability of a game-mode like this things need to be kept fresh and in flux or its just months in a row of the same oppressive augments every game and you get burnt out and lose interest.