You know what i think you should do at 50? Go BOD and farm the mobs there, king kong/Ogre, those have chance to drop a 50 blue and mobs there are awesome exp. That's what i did at 50
My Fighter is 46 and i solo GGk in Cp but lvl 50-51 is not good for farming ggk or grinding because, when i kill ggk i get 5k and it's lvl 45 your 50 or 51 so it will be like 1k or 700 exp im not sure. ._> But yeah Try Bonds of Darkness Way better exp. Boss in there is Chife Guard or as some say Tk.
Well it's not gonna be good exp, but it's one of the better bosses in the game to farm, along with GOC for mid-levels. Especially since it drops mighty/slash sets, which sell for a lot even with fail stats.