Despite riding a touring bike, I have found myself at the sharp end of a few of the audax I've done. I see more carbon bikes there (Treks, Pinarellos, Bianchi, etc), and nobody has complained about comfort.
I'm currently torn between a Domane 4.3 and a Madone 3.5. The former takes 25mm tyres and guards, the latter 23mm and guards. The Domane has the decoupled seat-tube that looks neat, but I'd need to be convinced it wasn't going to go creaky on me. I could get a Woodrup with Tiagra for similar money, but pretty as it'll look, I really want something properly light and nippy. Plan is to do LEL on whatever one I end up with.