as ive posted here before,
i am boosting a lock/pally and priest. with a 70 mage.
did SFk, SM Cath and also ZF.

they stayed in ZF till 48 and uptill then it went good.

i went to BRD. added my 2nd 70 mage. but that nerfed the XP by half. so im now with 1 mage in BRD, only clearing the first part with all the mobs together.

im thinking it goes really slow now, but there is no other instance atm.
during 1 day in the instance (about 8-9 hours) i went from lvl 48 to 53.

i think ill stay in BRD till at least 56 and then maybe LBRS/UBRS.

sad is though that they get about 100 xp per mob in BRD if im boosting with 2 mages, and 200xp per mob with 1 mage present. (SM cath gave also about 100xp per mob at lvl 30 to give an idea off the difference).

So im thinking maybe i need to go up a notch to an instance where the mobs are 5 levels higher then my chars, to gain more xp.