I have a 750Koa and a 700BluMoon.
You obviously have more tonal options with the 750, plus my 750 is 1/2 lb to a lb lighter than the 700.
The build quality is very similar, but for some reason I can't explain, the 700's neck feels perfect. They should feel the same, but I can feel a slight difference, also I had to polish some fret ends on the 750(very slight fret sprout). Never had to on the 700, and they were made the same year at the same plant.
Both are great basses though, and not just for the money. The build quality is on par with anything MIA, IMO. I can forgive the fret sprout, because that can happen on a maple neck and doesn't necessarily reflect bad QC because it likely happened after leaving the factory. Plus is is an easy fix.
That just my experience with both.
I have seen some complaints about the 750QM quality, but I never had any trouble with my 750KA other than that little bit of sprout.