What is your budget? Audax bikes were traditionally touring bikes. Relaxed geometry, stable and all-day comfortable. The maximum average speed allowed meant why take a race bike that will beat you up. Longer rides added the requirement for mudguards, so larger clearance also rules them out. All-day comfort also means larger tyres.
Touring bikes can be, well, a little dull. So along came something called an “Audax” bike. Steel frame, but slightly more sprightly geometry; shorter wheelbase but still capable of mudguards and 28c tyres. Dawes and Thorn were some of the first. And others have followed. Along came carbon forks and finally carbon frames.
For me, if I was you and thinking about riding 100-400k Audaxes, I’d look at something lighter than the genesis. In fact the carbon bikes by Tifosi, Hewitt and Pearson would be my choice. Or a Giant Defy, which might struggle to take proper fixed mudguards.mudguards. For sizing, I agree that you are a 56 virtual top tube (M/L for Giant). For me, if I was riding a 200k tomorrow, I’d ride my fixed wheel Kona, which is steel with carbon forks, Schwalbe Marathon Plus 25c and full fixed SKS mudguards. Sub 10 kilos. It’s the little things that add to comfort that matter most; carbon bars and seatpost for vibration, for example.
Finally, a Barley saddlebag is now mandatory. Saves a kilo over a rear rack and can take a cheese sandwhich, flask and coat.