I have finally found a pair of shoes that I can recommend!
They are from the Merrrel barefoot running range and I’ve found them to be both comfortable and suitable for running over fairly rough ground. They have plenty of room in the toe area, so no soreness there, and they are flat, so it allows full movement of the foot so allows you to improve your running.
They take a bit of getting used to, being so flat, but after three weeks of use my calf muscles are just about to stop aching. I’ve managed to do some longer runs than I was doing before, and I have had some time off with a virus, but today I ran one of my routes a minute faster than I’ve ever done it.
The extra spring you get from not having a thick heel is generally speeding up my runs, and I can run downhill much faster and easier, again because there is no clumsy, wide, thick heel in the way.
And if you have read my book (available at http://www.how2runfaster.com), you will see that downhill running is one way of increasing your running speed