According to Easton, CNT bars are fine with bar ends and the warranty is unaffected by their use so long as you use a particular clamp type (see the easton website) – I think they’re the only manufacturer to state this mind.
As for what they look like, who cares! I ran carbon bar ends on my old CNT risers for years – worked well and looked fine (imho).
I have to say though, after damaging the bars/ends in a crash last month and replacing them with some monster-wide 09 CNT low risers, I haven’t missed them since.