I used a similar Gregory pack, but a mens version, before. I guess it depends on how long the "long" trek will be. In my opinion, the size of this pack is great for medium range treks, from 3-4 days. If you are careful in what you pack, you could stretch it to a day or two more. If not, I would recommend a larger pack.

The gregory brand is a solid label. I've never had a problem with their packs and they tend to have POCKETS!! The ripstop fabric should withstand the beating the A.T. tends to give some people in the more rigorous sections.

HAVE FUN ON YOUR TRIP!

This pack is very comfortable and is one of the best of the Gregory line. If your question is related to the pack's durability I am confident that it will hold up for the 4-5 months on the AT. It's a very well built backpack.

A simple answer for you: YES!! This is an amazing pack, it should last years with a little common sense and with a little TLC when you get home from your trip. Have a great time! We are thru-hiking the AT in 2014.