I have been diving with the Mares Volo Power fins since OW, and they were showing a lot of wear. I wanted a smaller travel fin so I bought the F2's. The footbed on the F2's is wider, and they are lighter than my Mares. Under normal conditions, the F2's are awesome and very maneuverable in tight places. They are also best suited for the frog kick in my opinion. My only issue was if you are diving in heavy surge or a strong current, they do not seem quit up to the task like the Mares. My next set of fins will be the Mares Quattro Plus, mainly because I dive in Key Largo a lot, where the current can kick up anytime.
The spring straps on the F2's is adjustable, so with a thick boot they should be able to fit, unless she has a small foot size.