I’m in the minority in that usually I’d always choose the survivability+ attack as I usually do. That extra tile for slow is rare to make a difference.
However, given the costume bonus, firing in 10, making her average, may well be worth the trade-off. Worst case she’s ready a bit early, just bring support heroes to keep her alive a turn longer.
I was lucky enough to get Furdinand and I am SO looking to seeing them play together.