I did not return the M7. The quality of the preamp construction will always give me pause. However, the playability of the instrument is very good for me so I kept it.
Once I decided to keep it I gave it it's first proper setup. Prior to this there was not enough relief on the neck and B & E strings buzzed on the 3rd to 5th frets. I opened up the truss rod cover and loosened the strings. Seeing as I was not having to tighten the rod I gave it a slightly larger turn that I would normally. About a 1/3 turn was the distance that the hex wrench could turn without having to reset it. As it happens that was right on the money.
Set up was easy and with the extra frets I was able to test intonation at two octaves on each string. Now that I fixed its neck and back issues the M7 is much happier.