Here's another factor to consider: some people will tell you that it's hard to raise your handlebars to a comfortable level without a lot of spacers. Others might point out that spacers are no big deal, and that there are other, additional ways of getting a higher handlebar position.

Some shops will let you test ride for a while. Why not try some different bikes and sizes and sort it out through experiencing the rides (preferably with an open mind -- prejudices and preconceptions can really get in the way)?

The comment above about REI is also a good one. They tend to be much easier about changes and returns than some other shops. If you are set on the LHT, maybe you can find some owners who will let you test ride.

Test rides can help to answer questions, sometimes better than thinking; or at least they can fill in some important information.