Hey there Sandy,
First off, this "damage the neck" business is utterly wrong, with respect to your friend who mentioned it. Not only are Taylor's dreds designed for 13-56, you can comfortably put these mediums on the GA as well which were designed for 12s. Taylor necks simply do not "get ruined" with such a common string option. You are perfectly good in using either the mediums or the lights (12s).
Another option to reduce tension, however, is to try Elixir's "medium-lights" which use the EAD from the med set, and the GBE from the light set. This maintains much of the bass, which is a wonderful thing for your dred, but may help you in fretting, barre or not.
And yes, do experiment with 80/20 vs PBs. If you have nano PBs in med now, going to the same set in 80/20 --as you likely already know-- will give you a brighter overall tone ...which may or may not be what you want, so think about what you're hearing now and ask yourself if you want to give that direction a try!
Finally, after you determine what gauge and string composition you personally prefer, take your guitar to a luthier who is authorized to work on Taylors. The reason for "authorized" is that these techs have access to the graduated set of Taylor shims needed to accurately/properly set up your neck for the
best possible action. Moreover, the "best" setup is not a "spec" but is the setup that works for
your style, your paick attack, and your fretting hand, so discuss this with your luthier. A truly
good setup is a game-changer for any guitar, and can easily transform a "good" guit into a stellar one. Hope this helps you a bit!
Edward