Agree with the test ride advice. I did that and ended up buying a carbon Trek Domane SL6 after many years on another comfortable but more stretched out bike, a steel touring-oriented. Definitely a more upright position on the Trek and the various vibration damping features also increased comfort on long rides significantly.
I recently rented a Fuji Sportif aluminum bike to do the Seattle to Portland 2 day event. It has geometry very similar to the Domane, but aluminum and none of the vibration damping plus 28mm tires vs. the 32mm I run on the Domane. It had rim brakes, so I think 30mm was the max tire size you could put on it - to get to 32mm (which I have gradually moved to over the years) on many road bikes (vs. touring bikes) you need to go to disc brakes, which I wanted to do anyway.
Anyway, the ride on the Fuji was much rougher and I definitely felt in on the 122 mile day in my upper body. If you are normally riding on smoother roads or trails, probably not a big deal - but you aren't, and comfort is high on your list, also ride a few bikes with the various vibration damping schemes that are out there.