I think it'd of just helped cement Doffy's downfall, if even his mistress is now standing against him. And the fact it's the former princess of the country on top of it all? Risking herself to buy Luffy more time? If properly explored, that would've been a lot bigger of a moment.
Though, I'll be honest. I absolutely love the fact Doflamingo parasite's Rebecca and Viola and intends to have Rebecca, girl who won't kill, murder her aunt. That kind of wickedness is just the best to see.
Nojiko's style is great. And Nami before just had more going on for her. Now she's just always looking like she's ready to hit the beach. It got boring after 1 arc.