I've run exclusively in FiveFingers (KSOs) and barefoot since early May. The FiveFingers are great on the road, and also for relatively smooth trails.

Now, the new trail version ("KSO Trek") isn't available in Europe yet, and is set to be very expensive -- you can pre-order it for 190 Eur, if you look around.

However, I just got a pair of Treks shipped from the US (for $105 + shipping), and ran yesterday's Ceiriog Canter in them, much to the amusement of my fellow runners.

They're light and supple, with just enough protection from stones, and plenty of grip for all but the most slippery surfaces. Weaknesses include a tendency to collect clumps of grass between the toes, and a long drying-out time, but the experience of running in them is so enjoyable that I'd still pick them over all-out fell shoes whenever possible.

I wouldn't use the Trek model for road-running, though -- the thinner-soled regular models feel nicer.