I don't know a lot about the ZG gear as I've only been in ZG a few times.
I've got no problem with the rate I'm getting gear from AQ20 though. The set pieces each require only one boss drop plus a bunch of trash-dropped scarabs and idols.
In any case - it's not like the bosses *only* drop the set piece materials
Edit: Also, the blues that you get from the quest are exceptionally good in comparison to other blues. Is your ePeen really that much smaller when one of your pieces of equipment isn't purple?