I run in mine exclusively now, have for a couple of months, up to 18 miles at once and about 30-40 total miles a week. I have KSOs. I can't run in them barefoot (ironically) and have to wear socks because the seams in the shoes rub on my (admittedly wide) feet in my arch. I'm really keen to try the Bikila - one review I saw said they really fixed the interior of the shoe to more like a soft lining with no seams.

I have another pair of Sprints that I wear for general use, and will probably use for short triathlons (easier to put on). I kind of wish I'd have got the classics, I think they'd be easier in general and not rub the top of my foot barefoot. Oh well, live and learn. Somehow I have a feeling I'll end up with a collection to rival my Keens.

If you consider them, to make the transition easy, you should strengthen your calves and ankles first. The first few times you use them for any length of time (other than "sitting around in them because I feel like I'm cheating and really have bare feet") the backs of your calves will hurt. There have been a couple of articles that recommend standing on one foot for 30 seconds, make sure your big toe and mid-foot don't leave the ground, and then with your eyes closed for 30 seconds. If you can't do that on each foot, build up to it, then several times a day.

I definitely felt a difference in my glutes, the inside of my thighs, and my calves (among other things). Now for me it's no more shin splints, no more hip pain, and a happier body in general.