I haven't ridden the Capo, but I own a Sputnik, and it is awesome.

Both bikes have carbon forks, black paint jobs (a silver option on the Capo too), Formula hubs, and nice frames.

I like the Capo a lot. The frame is one of their road frames (just with fork ends) that has been around for years. I like aluminum more than steel for it's corrosion resistance because I beat the **** out of my bikes. I think they are equally matched on components.

The Sputnik still comes with cranks that are too long (for me at least), but that's the worst thing about it. I also didn't like the lockring, cog, saddle, or gearing on the 06. The cog and lockring are easy and cheap to replace, and that will let you change the gearing. The saddle is a different one for 07, so I don't know what it's like.

They are both nice bikes. You should try to ride each before making a final decision.