Thanks all for your input.
This is my current road bike: 2010/trek/madone47wsd. This is the men's bike I had before it: 2003/trek/2000.
I am 5'7". The above bikes were both 54.
I went to the LBS today. They didn't have a Checkpoint in a 54 for comparison. They offered to let me try a 54 Domane but I declined for now because it was raining. The reason they wanted me to try it was to show me that the frame geometry of the current bikes is way different than it was 7-8 years ago. (Apparently my 2010 bike is retro, not "modern." Go figure.)
I am really not happy with Trek right now, because I think their website is intentionally misleading instead of being straightforward about a big change in their products. However I am happy with the bike shop, and have a long history with them. And I think they are really mostly a Trek dealer. I think I am willing to try out a Trek because of my relationship with the bike shop. If I can't work with their fitter to make a Trek work, I will ask about the other brands. Of course I still haven't heard from the company that handles the free hybrid bike to find out what they will substitute for the 2018 sold-out bike on their website. Until I get that information, I will not move ahead with test rides, etc., since the whole point here is to save a chunk of cash on a new bike.
The main reason I went to the bike shop today was because my Madone's rear wheel squeal (or Mavic moo, as my friend calls it) is worse now than it was before. I rode 58 miles yesterday and it mooed a lot from almost the first mile. Other than that, it was a great ride. I was the leader and I posted it on two bike club schedules. I ended up with 19 people total. And for the first time in a long time I ran out of cue sheets at a ride -- usually most people use a Garmin or Ride with GPS on their phones, so they don't take paper cue sheets, but yesterday most of the riders were old-school low-tech (as I am). Fortunately I knew the route well enough that I could give my cue sheet to someone else.
There was rain early in the morning but the roads were mostly dry by the time we started the ride. Most of the other riders were faster than me (I ride at the low end of the ride category pace) and I think most of them skipped the first rest stop. So I didn't see more than half of them after the ride start. Which is not ideal, but doesn't really bother me. I still had a couple of people to ride with and the weather turned out to be great, with temps in the 70s, partial sun and humidity lowering as the day went on. We had a brisk NE sea breeze when we were near the Chesapeake Bay but that was only for a few miles. Overall it was a great day and I'm glad we had nice weather for a change.
Now it's raining again, and will continue to rain for a few days. So it was a good time to take the bike to the shop to try to resolve the Mavic moo once and for all. I started a different thread on that, and will update it.