Big drawback is missing cookies cafe pie shop in Golden City, Misery.
Missouri, Kentucky, and to a lessor extent Virginia have the most difficult hills on TA in my view. All the climbs out west are a piece of cake at 5-8% modern graded, just longer. I took a quick look at the elevations and grade of the Eastern Express, it looks easier
I am not sure I would want to miss Pueblo up to Walden although Poudre Canyon is nice
You should be able to hook up with TA in Kansas using only part of the Eastern Express..??