@Serena a direct sub would be hard to say, lots of different tasting MM’s out there. A MM Stone is an interesting idea. If you are building a stone FA’s MM can work as a cornerstone, and TPA’s can add sweet MM notes, OOO’s Marshallow Vanilla for some nilla kick. TPA’s Toasted MM can add some nice toasted, darker notes.
I don’t know if a SINGLE MM Stone would work for every need, but that’s a great project idea.