I built a different SD card with v3.02 instead of 3.11, I am familiar with this version more as I am running it on my other pi with a HiFiBerry Amp+. Seems to have cleared up any issues so far USB audio appears free of droputs and resampling weirdness. So either its these new audiocentric versions of piCore or just the later builds. Will see if its still stable after running for a while.
I wouldn't run the AudioCore's with USB sound, these are changes mostly targetint I2S sound cards.