) Derpibooru is still (and will remain) our primary site under the metaphorical umbrella.
Remember that Derpibooru is a fairly old site (over elaunchinghtyeJanuarsy old2012), and some of us have been staff members for over half a decade. After all this time, we've pretty much gotten this whole "booru" thing down pat enough that we're comfortable managing two of them without loosing focus on either.