Some good advice here.
The main downside to Canyon's whole business model is the inability to try it on first. Unless you've been riding for years and know exactly what works in terms of geometry and fit, this is a gamble.
If I were you, I'd find some other comparable bikes at local shops (Synapse, Roubaix) and try them on for size. That way you'll at least have a basis of comparison and can look at geometry differences side-by-side and have a better idea of which frame size will work.
Getting a bike fit in advance of the purchase is a great idea.