Given that you want a fast feeling bike, don't plan much offroad, and have a bad back, the Diverge probably fits the bill better. They tend to have a centimeter more stack which will get the bars higher while having more of a race-influenced design.
Though you have your mind more or less made up, a bike I thought you might enjoy is the Masi Speciale Randonneur.
Just my 2 cents to add to the great responses already added. Recently bought the Tamland 1 (2017 model) and the only change made was the tires as they standard setup is "tubeless ready". Replaced by the shop with Panaracer Gravelking 38mm which feel amazing and wide enough for everything. Also swapped pedals but it was nice that they came with some platforms which most come without now.
Steel frame is totally the way to go in my humble opinion but test em out back to back. I'm sure carbon would be great too but for 2k you may be better off with steel or Aluminum and a second set of wheels. I love the way the tires and frame soak up the bumps and I wasn't worried about the lightest bike possible as I'm going to be using a racks and/or fenders when commuting, touring etc. I'll leave everything off for trail riding, maybe but so far, the only time I won't ride is for road rides and lots if hills where I'm not touring i.e. century rides, fast group rides, hill training etc.
I think the 2 x may be better for me long term with more range of gearing and cheaper cassette changes! I find I go through drivetrains quickly. 105 on this Tamland 1 is amazing!
Let me know if you have any questions. Good luck and you can't go wrong. Jeremy
I almost bought a Tamland. I was not crazy about the color and it was over my planned budget by too much. Looking at the site, it looks like it's steel with carbon frame.....similar to Salsa Vaya Apex. My Vaya is all steel and Tiagra. The Tiagra shifts great if you wondered about groupos. A my local bike mech said he thinks it shifts almost as good as 105.
Tamland is Reynolds. Fork is carbon. Most posts I have seen the price is way below MSRP maybe 1200 USD. I paid 1500 CAD which is a lot less than 1800 USD.
Tiagra and 105 should be very similar as far as shifting performance.
