Basses come, basses go. The one there is not, the chase only there is.
If you will always reach for the MM then the other two are not going to be used. Flog them (or trade - better VFM) and get another MM as a backup.
>I know it's subjective, and could be a sprawling, non-sensical ramble, but that's BassChat isn't it?
Ain't THAT the truth.
In 40 years of playing I have NEVER been asked "Do you have another bass to try for a different flavour" in a band or in a session. I am sure those situations exist but I have not seen it. For my personal satisfaction, yes. To the rest of the world a bass is a bass.