Cool idea and seems to be optimized perfectly. I really like it.
I think the conversion actually improves your damage a tiny bit since you have 3 times more %Vit than %Fire (3k vs 1k).
Hmm, Chaos RE is not that terrible once you commit to it fully I think (you can stack the most flat damage and modifiers out of all damage types and squeeze in Oblivion for more DPS). Although 1) the dagger was nerfed 2) my toon was a bit fantasy 3) tested only in Crucible (but it was very durable there) so who knows how it feels now 