If this was AS5 I would go for it, but carbon is not as good a conductor as silver by a huge margin.
AS5 is still the best value by far for thermal conductivity.
AS5 performed slightly worse than MX-4 in a test by MaximumPC of 17 thermal pastes [maximumpc.com]
summary page [maximumpc.com]
It however is a bit more complicated as some pastes lose some their heat transfer efficiency over time and some perform better over time. I've read AS5 improves after the initial application, not sure about the others.