I don't think 2-stroke oil "precipitates" out of solution.  It's never
happened that I can tell on my chain saw or outboard.  Haven't heard of
it on anyone else's outboard.

As to whether MMO is better than 2-stroke oil, MMO is advertised mostly
as a detergent.and an OIL additive.  NOT as a fuel additive AFAIK.
2-stroke oil OTOH is the ONLY lubrication a 150 hp outboard EVER SEES.
MMO doesn't advertise that, and if you were to call them up, I bet they
would VIGOROUSLY OPPOSE substituting it for 2-stroke oil in your
outboard.  I'll mix the WalMart 2-stroke every time.

Around draining excess oil out of sumps, I'm wondering if perhaps that's
a sign you're mixing too much MMO/2-stroke in with your gas?  Perhaps go
from 1 oz / gal to 3 oz / 4 gal or 2 oz per 3 gal until you're finding
just a little extra in the sump.

Just a theory ... Jim S.