See if you can rent some AT boots, and get to "feel" the difference in them as opposed to alpine boots.
I like my Denali Xt's, and that is because I did my homework, and tried a few different boots, and in essence, this boots fit ME the just right, and were good for me on long approaches, and tours.
Thats all I can say for now.
You are doing the right thing by asking questions here, I just wish I had all the answers, but you'll find something soon.
Thats all i can