Well, I suppose it's time to move on. I've been practicing full butterfly shooting for about a month straight and it's been a roller coaster - some days I swear I couldn't hit the broad side of a barn, other days I've been terrifyingly accurate.
But, after putting serious thought into it, I conclude that I just can't seem to get a comfortable pouch hold. Having a normal pinch grip works for a few shots but even with a low draw weight the hold is still an awkward over extension of the wrist and it gets dicey in a hurry. I tried experimenting with a couple other pouch grips, but either couldn't get a consistent pouch release, or in one case speedbumped over my thumb and launched the pouch into the bottom of my jaw, left a big juicy bruise.
If anyone has any tried and true butterfly pouch holds for full butterfly, let me know - otherwise it's back to half butterfly for me!