Here's my dilemma. I currently have a steel Lemond Poprad set up for commuting with a rack and lights and an aluminum road bike. I'm thinking of getting a Ridley x-trail which would replace one of the bikes and also be used for gravel, lousy pavement, and very steep rides.
If I sold my commuter I'd get a rack for the Ridley and possibly a set of wheels/tires for city riding.
If I sold the road bike I'd get another set of wheels with road tires for the Ridley.
I don't do any racing besides hill climbs and some hilly group rides so a lightweight road bike is a priority. How close can I get an x-trail or other gravel bike to a road bike?
The Ridley is for me, and will be for you, an excellent road bike. The geometry is almost identical to the Fenix as well as other manufacturer's fondo models. But with clearance for much wider tires. So for an adventure bike it leans very much toward the road end of the spectrum though still extremely capable off-road. I us mine regularly on the road - both group rides as well as those w/a lot of climbing as it has lower gearing than my road bikes. It will also be my go to bike for road centuries.
The X-Trail will likely be a bit heavier than a pure road bike mostly do to the disc brake setup and the frame could be slightly heavier too. And, depending on which model you buy (I have the Performance CR1 in carbon) you may want to change some of the components to lighter ones. I think you could get to sub 18 lbs w/a light set of wheels/tires and carbon bits here and there. I'm not sure if it will be optimal for a hill climb race but should be great for general climbing and group rides. It's pretty much a thoroughbred bike and would be a shame to be used for commuting.
I used Open Pave in 27c, tubed, on the road for a while. No issues, but I sold them to a friend as she needed some tires for off-road use on her road bike w/tight clearances. Lately I've been doing mostly mixed riding so have been on Schwalbe S-One in 30c. A great tire - for both on road and dirt. I'm pretty sure it would be a great commuting tire too. After I complete an upcoming event I plan to get a pair of Schwalbe Pro-One in 25c for the road.
They do make the X-Trail in an aluminum version so if you go the commuter route that might make a good choice. Performance Bikes is having a 30% Performance Points incentive coming up soon that would be a great time to buy from them - worth $840 on the CR1. That could buy a pretty nice set of wheels.
I have an X-Trail and love it. It gets used a fair amount on road, but definitely shines off road. I would however not recommend putting a rack on it. I am sure it could be done, but I would not recommend it. A new fork with rack mounts might be something that could be considered, but that is not what the bike was designed for... in my opinion.