The Winter 2013-14 issue of Momentum (the magazine put out by the National MS Society) has an article called "If the Shoe Fits" (pages 27-28):
http://www.momentummagazineonline.com/shoe-fits/There is also a list of 9 tips on footwear that isn't coming up in the online version. Here are those that I like best:
1. Light tread A heavy tread creates more friction on the ground, and the foot could drag
2. Light weight A heavy shoe takes more energy and effort to lift when walking.
3. Secure fastening String or elastic shoelaces and Velcro adjust for a more custom fit than a slip-on.
...
6. Firm heel counter Press on the shoe at the bottom of the heel--it should feel solid, not soft. Skip loose sling-backs, flip-flops and clogs.
...
Sources: Monica Wainio and Dr. Terrence Philbin
Also, back in 2009 there was this thread on MS Speaks, about women's high heels and foot pain:
http://msspeaks.easyphpbb.com/viewtopic.php?t=2854