Sounds like fun, although when the S3X hub came out there were some concerns about quality. I would rather have a WT5 myself - a three speed fixed gear just seems bizarre. To be fair, I do love bizarre bikes. It certainly is a cheap way to check out the S3X thing.
If BikesDirect offers an S2C Kilo, I don't think I'll be able to resist. It's probably going to cost me $350 just to build an S2C wheelset this summer (to be fair, it's going to be a sweeeeet wheelset. Just need to choose between Aeroheads and PBPs).
Are you listening, Mike?