I just tested some 1.75mm natural (no colorant) MG94 ABS that was extruded without much care for moisture, and I could curl it into a 1" diameter circle without breakage.

Yes, moisture can definitely cause brittle and bubbly filament. The moisture is likely gone from extruding once, but it doesn't hurt to dry them further. Most folks use a food dehydrator, they're pretty cheap from Goodwill or similar.

Thanks.  Drying in the oven seemed to help a lot. I still get enough periodic flaws in the filament though (visible while extruding) that it sometimes breaks when coiling onto the spool.  This seems to be much worse when using masterbatch.  I'm using black from OSP, which I was using at 50:1 and improved when going down to about 80:1.  Is this normal?  My colored filament has always been a little brittle before and sometimes broke when manually winding, but it's a bigger issue with an automatic winder since I have to stop extruding when this happens.  I'm going to add a cutoff switch when a break is detected, and maybe switch to a spool with a larger inner diameter and change its orientation so it matches the natural curl when extruding.

Also, if I chop up and reextrude, do I need to dry the resulting filament or would the previous water already be expelled? If so, what is recommended?