I feel like I have those exact pains, but I'm not sure about racing flats.. I usually run 5+ miles (not racing) and flats are more for shorter distances (and racing).
What shoes do you wear for marathon training?
p.s. Are those exact flats still purchasable anywhere? Can't find them online (size 11').
I wore the racing flats for all road runs, including marathons, for years. Now I wear NB Minimus for both roads and trails. But the principle is the same. It's flat, flexible, light shoe.
The racing flats I mentioned are designed for racing, definitely. But the idea is that you wear them for all road runs, fast or slow, as a means to changing your running form.
What shoes do you wear for marathon training?
p.s. Are those exact flats still purchasable anywhere? Can't find them online (size 11').