I use my Sidi mtn shoes with my road bike. I can walk in them decently and while they aren't as stiff they fit the bill well enough. I do not, however, race road bikes nor do I care if I don't get every scrap of pedaling power possible.
Road shoes=stiffer, cleat sticks out, harder to walk in, made for speed, you shouldn't be walking much in a road shoe anyway.
Mtn shoes= a little more flexible, recessed cleat, tread, easier to walk in for those times a hike-a-bike is necessary.
As far as the pain goes there are more reasons than just shoes that can cause your problems. That's an area I'm not well versed in, but perhaps a little more info and some of the fine people here can give you some ideas?
Last edited by singletrackmind; 03-30-2009 at 06:18 PM.
I used to have an open mind but my brains kept falling out.