A friend's daughter has this. She is on my daughter's dance team. Her extra navicular bone is on the top part of her foot, right over her instep.
So far, they have been able to manage the pain by using a wrap - it almost looks like an elastic ankle support, but it has extra elastic straps that support her foot and ankle. During intense periods of rehearsals, the girl has a lot of problems with pain. So, their next step is the surgery, too. I think that they were told that recovery takes about 12 weeks.
Good luck. Get a second opinion if you are not sure - the surgery seems like it should be a last resort type of treatment, but only you and your doctor can make that decision.