As the bloggers at Natural Coaching suggest, it is, actually, about the form, and not the footwear. And I agree totally. I recently bought a pair of Vivobarefoot Breatho. I was wearing them around for a few days, did some shorter runs and finally decided to go for one of my usual afternoon runs, 45 minutes on the gravel/dirt road. (Yes, I'm in my under-45-mins timeframe yet). I, of course, wanted to run "properly", landing on my forefoots. I finished my run and I was pretty satisfied, actually. It felt great! Until day after. I've got such cramps in my calves that I couldn't longer that a minute the next day. Now I'm doing 10-15 minutes easy runs every day, hoping to get back into 45-minutes regimen within a month.
So, it is actually about good running form, not the shoes.