My point of view,
Split your MR in 2 to CO and DL,
Delta is not offering 1st class, but reward need less points than CO for partners.
CO: 100k Bizz
150K 1st
200k AF Concorde
DL: 80k Bizz
160k AF Concorde
Don't forget the partners, AF, AZ etc...It's much easier to leave from Canada to Europe with a partner than US on DL or CO!