I may be wrong, mate, but my take on this, having a bit of experience of pure and non-ped whippets is that the non-peds suffer more foot problems than the pures is simply down to the fact the are far, far faster and , usually but not always, racier built, more muscular, for their size, (height).
Its a definite that the non-peds suffer far more gracilis problems as well than the pures, again I put this down to the speed difference.
Just my opinion .
Cheers.