I’m 5’11 and the 55.5 fits me spot on.
Don’t worry about the ‘CX’ downsize thing. Just find what reach is good for you.
I also like the way they do their internal routing. Rattling cables are a pet hate of mine. The have super tight ‘Gizmo’ routing, keeps the cables tight – no rattles at all
And the paintjob is superb.