The Cannondale C1 (Tektro) Carbon Fiber brakes as used on the System Six have to be the best brakes I have ever used on a roadie.

I don't know that I would go that far...but I did say in my review of the SystemSIX a while back that the brakes were every bit as good as the Record on my Roubaix and the Ultegra and 105 5600 brakes I have used on other bikes.

Tektro + Koolstop pads work just fine. Swaped Ultegra's for Tektro RX40s due to a cable route issue and there is no difference is stopping power. Putting a set of Tektro 750's on my new build.

OP. What wheels are you using? Rim brake surface has as much to do with stopping as the claipers themselves.

From what I have used, I can say that the quality of the caliper is a big factor along with the pads. I used to have Cannondale Omega brakes with Dura Ace pads, and they stopped like garbage. For some reason, I could never dial out the flex that occured once the pads contacted the braking surface. You could pull the brifter a good 10-20% more with moderate effort once the pads were firmly on the rim. However, I now have full Campy Chorus on my bike and the difference is like night and day. There is almost no flex whatsoever in the brake. It feels like an on/off switch, which I love love love. Also, I've noticed that Campy uses a harder compound brake pad.

The Omega (Made by Tektro) was indeed garbage. They were made of tin and felt like it. As you said, very flexy.

The Tektro R750 is the same brake that Cannondale is using on the System Six (Badged as the Cannondale C1). Very nice indeed and the carbon looks beautiful.

I noticed that Biketiresdirect has dropped their price on the R750's to $149 now (with Kool Stops included).

The R750s are very nice and work well. I am running two sets of them on a couple of road bikes. They are lighter than Campy Record and are dual-pivot front and back.

yeep!