The changes from the original build are upgraded cranks (Truvativ Omnium), Easton EA70 46cm shallow drops and a KMC chain. I'm already through the rear tire and after only three months of riding I need a replacement.
What I find is for the type of "fitness" riding I like to do, this truly is the choice bike. It climbs better than any mountain bike I own and descends any non-technical trail just as fast. I am faster on this bike than any of my other trail bikes when considering equal terrain (obviously my full suspension bike does much better on technical downhills).
I do find myself wanting gears, though. There are some climbs that are just not do'able on the singlespeed, so I resort to walking (which I hate). With this kind of climbing geometry, it'd be so awesome to shift up. There is one hill (Coyote Peak in Santa Teresa County Park) that requires an initial walk, but I can clear everything else.
I think if I can go back, I'd build a geared bike. In fact, if I would've listen to my brother, I would've built one cyclocross bike from the beginning instead of having my Surly Pacer AND my SS 'crosser. Oh well...
It's nice to have the variety of bikes that I own - and I do ride them all. However, when you ride only a few, it makes you wonder if all the others are necessary, especially when you've bascially found "The One".
To me, a cyclocross bike is like taking all my favorite attributes of an off-road bike and forming Voltron. And in case you didn't know - Voltron is BADASS.