I really loved the SBH when I had it. Looked awsome, there is nothing better than swingin around a big Axe or Halberd. The PGT used to be a really really good weapon. It has been nerfed back alot! I wish they would come out with something like it again for T6/T7.
But to answer your question I would hang on to SBH and do the quest for PGT and get another decent duel wield. and use them both depending on what you are doing. I carry 8 weapons with me,
i would get more but T7 is comeing out very soon so im gonna wait. if it is a harder enemy you might want to change to the PGT for the buffs it gives you. Before they nerfed it I swear i was untouchable with my avoidance and the buff from the PGT, it was great!
I just really like the look of a HUGE 2h weapon. thats just me. but go for both of them.
I cant remember what lvl the serated bone dirk is but that is another HQ duelwield