Not really about weight more comfort and if hanging a bag off carbon was a bad idea. It’s been fine so far.
The saddle is a Romin, the carbon has less padding but seems to flex more. The ti slightly more padding but feels more rigid.
Maybe I’ll ride the ti on Sunday and see
Don't understand cable question, is it di2?
Carbon saddle rails probably be fine but gain is trivial. Is Ti stronger? If so I'd take that.