Rob, I went or the alloy sumo XCR.
IIRC the carbon is heavier than the alloy, I spoke to one of e guys at USE about it and they said there’s no difference in performance the carbons just for those who want a bit of extra bling.
Give USE a ring if you need more info or have questions, they’ve got brilliant customer service. I sent them my 20 year old SX (that I bought from the classifieds here) after I tried and failed to service it. They took a look at it, told me it was too old to do anything with and then offered me a new post at trade. 😯 i really didnt expect that, so I got the XCR.