I'm running the Omega X up front and a TRP T925.1R on the rear. The Omega X is working fine up front, but I didn't get it to work well on the rear. It gunked up extremely fast on wet roads and didn't release properly - maybe with extremely good cable routing you can get it to work well, but you probably still have to clean it quite often.
With the TRP you can't fit the rear brake cover, but according to Cervélo it doesn't make an aero difference (with the Magura brake). I believe there is a slightly different version of the TRP that allows the cover to be installed.
I have actually thought about ordering an eeBrake as that *might* fit on the rear and give you both a small, light, and well-working cable-actuated rear brake (if it fits).
As a side note, I actually had a commissaire at elite worlds object to the magnetic front cover of the Omega X on a bike pre-check. Got to race with it, though (as did at least a woman). I also believe the Professional Continental team Cofidis is using the Omega X at Tour de France, but Nick might be able to shed more light on that.
With the TRP you can't fit the rear brake cover, but according to Cervélo it doesn't make an aero difference (with the Magura brake). I believe there is a slightly different version of the TRP that allows the cover to be installed.
I have actually thought about ordering an eeBrake as that *might* fit on the rear and give you both a small, light, and well-working cable-actuated rear brake (if it fits).
As a side note, I actually had a commissaire at elite worlds object to the magnetic front cover of the Omega X on a bike pre-check. Got to race with it, though (as did at least a woman). I also believe the Professional Continental team Cofidis is using the Omega X at Tour de France, but Nick might be able to shed more light on that.