DRK did suffer a loss of mana regen, however it was in the unique position where it didnt even need tank stance to draw its aggro. This is cos after the buffs towards the middle of SB their aggro combo finisher not only got upgraded so when dark arts it would do the same damage as a dark arts soul eater (meaning you only lost 20 potency across the whole combo discounting the mana gained from syphon) but the DA version of power slash had a ridiculously high aggro modifier, basically double that of the other tanks aggro combo finisher, on top of dealing more damage, and cos it wasnt crazy enough it had a built in "flash" effect generating even more aggro. On top of that DRK had a crazy high aggro mod on Dark Passenger as well which was dps nuetral if you had a smn in your party. This made aggro on drk even more braindead than most other classes as you didnt even need to touch your tank stance to generate a shit load of aggro, which is even more of a reason why aggro needed to be ditched, the entire mechanic existed for your opener or add spawns/aggro resets, and it wasn't even engaging. Bringing back aggro managment on tanks is a mistake.