Mrs flap_jack has a Ruby. I have a Diverge. Both carbon, superficially they look similar. The Diverge has much more ‘heft’ about it though, which I hope means it’s stronger.
Mrs flap has done light off-road on the Ruby and found it fine, and it flies on-road.
You can’t attach racks to either.
Finally, why wouldn’t you want a smart-weld aluminum Diverge? You can attach rack/luggage to that…