I have been reading your recent blog posts on running and in particular the endless controversy of barefoot running. As long as you use it in a moderate way, your chances of success are much higher. Try to avoid running in Five Fingers on concrete, as not even the Tarahumara of "Born to Run" fame would enjoy their knees and soles pounding on a surface that doesn't give at all. There is nothing more painful to watch than a jogger in Five Fingers running down the sidewalk clomping along - there is no way that this practice is better than having a little polyurethane between you and the rigid pavement. [JF note: I agree. These "shoes" seem an ideal match for a nice rubberized track, like the one at American University where I run when in DC.] When you wear Five Fingers on trails, there is a tendency to trip on rocks and roots so make sure to be aware; I know a diehard who wasn't comfortable still after 6 months.Thanks! And for trip-down-memory-lane purposes, here is what some of those antique shoes looked like -- an updated Asics shoe recapturing the late-1960s design that I remember from my Adidas of the time, below. Compare it with today's Hummer-style contraptions. More on the evolution of shoes here and here.
I'm not a card-carrying member of the barefoot/minimalist school; I think if your foot strike is fairly neutral or slightly pronating a minimal shoe is definitely the way to go, but I'm not sold on Five Fingers or the notion that forefoot strike will solve everyone's athletic injuries. Everyone's heels, including Chris MacDougall's, strike the ground on every stride to some degree. Most of the athletes in my club (and indeed, many pros) have moved to a slightly more minimalist way and do a lot more training in what appear to be racing flats - like the old minimal shoes that Asics & Nike sold in the 70's you might remember. Our track that we train on has a lovely grass infield and I almost always run 2 miles after our workouts without my shoes to keep my foot muscles strong.
As for the awful annoyance of achilles tendonosis, moving away from the trendiness of barefoot running being a cure-all, the time honored practices of reducing inflammation (ice), strengthening the tendons through exercises, and trying to avoid situations where the tendons suddenly have to change length (especially when you get out of bed) should always be part of your therapy cocktail alongside those Five Fingers.
I hope the injury gets better, and it usually does.