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!
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.