This is my first post, and as I can’t seem to find any recent posts about Vibram Five Fingers being used as primary footware for backpacking, I figured I’ll give it a go. Please forgive me if there is in fact a recent topic for this.
I’ve only started going backpacking and have been on 2 trips. The first section of the Long trail in Vermont, and the Pemi Loop in the White Mountains. Both trips I wore Vibram Five Fingers as my primary (and only) footware with heavy pack weight and I was often asked on the trail how I liked the shoes, did they hurt, and (from the older fellahs) are you insane? The answers being sort of, no, and slightly.
I should note first that I run in VFFs 3-5 days a week on hard pavement, and have been for the past year. I believe that this is what strengthened my feet enough to not hurt at all on either of the two trails, even over stones/roots with 20 – 30 lb pack weight (haven’t the money to lighten the load yet, so don’t cringe too much).
Even though my feet never particularly hurt, the reason I only kind of liked them was because even in small puddles/mud my feet would get wet. I wore toe socks on the Long trail, and let’s just say the socks were demolished with all the mud. On the Pemi Loop, there was less mud, and I didn’t wear socks, but there were plenty of small puddles where my feet got wet… Ultimately on both trips my feet were wet nearly all day long every day… And very dirty.
It is noteworthy that the shoes themselves held up perfectly and they do in fact dry out very quickly. They are also pretty grippy on wet rocks and it’s extremely easy to keep your balance on uneven terrain because your feet wrap around the ground and not teeter on top of it. Ultimately, though, for anybody wondering how they apply to backpacking, I suggest that you strengthen your feet well in advance, bring warm dry camp shoes, and prepare for wet feet on shoulder season treks.
Sorry for the lengthy post, but I had found it very difficult to find people who had actual experience backpacking with Vibrams and felt they needed a thorough  shakedown. This all is based on my own personal experience so ymmv.

