I have ridden the newest (actually, oldest) one about 150 miles in the past few weeks. I don't have an odometer on it yet, so I'm just guessing at that mileage based on google maps. So far, I've liked it. I've commuted to work (20mi round trip) a few times, and swapped out several parts as they come available via craigslist or been borrowed from another bike including the handlebars, seat, pedals and various tiny parts. I replaced the original crank that I bought on craigslist because it was slightly eccentric and was causing the chain tension to vary too much. I also got a new set of front brakes (not using rear brakes on fixed gear bike). I tried a few things that ended up not working. I now have a craigslist parts bin of my own to sell off soon. Half of what I originally bought will be replaced with new stuff eventually.
Tomorrow, I'm going to LB Houston after work to take the old Cannondale rigid bike out for some dirt riding on some big knobby tires.