So this is more an interesting fact than anything overtly useful but I discovered that thanks to the 6.0.2 rebalances the legendary staff dropped in the kael'thas fight in Tempest Keep was more or less as good as my level 90 weapon as well as having the awesome use effects.
This led me to wonder if any of the other old gear has been improperly balanced - especially legendaries. Something I shall be looking into and you guys should too
Cheers!