I have to agree with
Lilian, the connotations will be lost on most.
If I have to choose, I would go with
Mercedes and
Edmond... I adore the name
Edmond, and
Mercedes is very pretty as well.
As you stated, though, you have pleanty of time! That's why I don't put combos in my signature- it could be fifteen years until I have children, and I'm sure my opinions by then will drastically change!