My fiance recently got a pair of the men's FitFlops and has been wearing them EVERYWHERE. He bought them because he has knee issues that no one has been able to diagnose so far and is hoping that they'll help strengthen his weak knee, because they work in all directions, and not just the "back and forth" that regular walking works. His knee injury is strange, in that sitting bothers it much more than running does, but has led to an overall cumulative effect that makes mobility painful. So far, no verdict yet. He says that they're as comfortable as his Tevas once you get used to the "thong" in the sandals (he's a guy, and so not used to wearing flip flops like us ladies normally are) and provide good support while walking. He hasn't noticed the "fit" effect, but he's a long distance runner, so his legs are already pretty toned. As far as his knee, he hasn't noticed an improvement, but he has noticed that the FitFlops don't bother his knee like other sandals do. He thinks that they would be comfortable for walking and standing a lot, like you do in WDW.
I would think that the dislocated toe might be the bigger issue, as you have to "scrunch" your toes a bit to hold flip flops in place, but if regular flip flops haven't been bothering you, I'd give them a try. I live in my $75 Keen flip flops, and they are by far the most comfortable sandal that I own; I was leery about spending that much on a flip flop, but I've learned that there is a big difference between the $5 Old Navy foam flip flops, and the really high quality ones, in terms of comfort.