I have a Francoise, it is a very small bag! The Marina croisette looks like it can hold a lot of stuff. I love the way the Francoise is a clutch, hand, shoulder or cross body bag and am very glad to see the shoulder/satchel system coming back into fashion. Marina is very feminine and casual, Francoise is far more formal a bag.
I don't think it would be too much to have both bags. The fabric and leather is so nice on the mini mono, my favorite LV fabrics [don't tell my epi bags I said that though].