What legs is your DD currently using? My DD's All-Stars seem to stay in place pretty well. The Schutts she had in 10U did not.I think for me significantly better is having the legs stay in place. Everything just moves around so much. I don't know how much shin protection is actually used in ball strike protection, if it is a layer of hard material and doesn't move I'd say that is a huge improvement in mobility.
And awesome that the FP legs are $10 more expensive!