Just thought I'd tune in on my similar experience. Sorry the post is a bit long!
I got my first pair of VFFs (KSOs) at the beginning of April and used them as my daily "shoes" after a week of transitioning from "regular" shoes. In addition to using them daily I did about a mile or two of running on concrete (the sidewalk) or asphalt every week with no real noticeable wear. To keep the smell from knocking someone out (!) I also usually washed them every other week with cold water and powder detergent in the washer. I never put anything else in the washer with them and I would just hang them up to dry.
Sadly, about two months ago I noticed the sole on both feet was really soft where the ball of my foot has been contacting the ground. The spot is between my big toe and the one next to it (on the ball of my foot). About a week later the soft spot became a dime-sized hole in both soles, then, around October 10th, I noticed (while running) that both holes had enlarged to about the size of a quarter.
I washed my (old) KSOs last night and went to REI today, exchanging my old ones for a brand-new pair. The soles on the new ones didn't look much different based on my quick side-by-side comparison. I showed the salesman my old (worn through) KSOs and he said he'd never seen someone wear through a Vibram sole like that.
As for the new pair, I'll have to double-check the sole thickness tomorrow to make sure they're OK before I actually use them.
As a bit of a side note, I jogged barefoot around my neighborhood and noticed that my body seems "trained" from wearing the VFFs to strike the spot were my KSOs wore out instead of a heel-strike. With the exception of the holes in the ball area both shoes showed very
little wear despite me using them daily, maybe that means I was striking that same spot while both walking and running? While I'd much rather go through VFFs than develop bad knees from a nasty heel-strike I'm hoping a bit longer barefoot run I'm planning on doing tomorrow can help me see if my stride changes itself when I'm barefoot so I don't ruin my replacement KSOs quite as quickly.
It's too bad that society doesn't currently "accept" being barefoot, for the most part. I do love my VFFs but it's going to annoy me if I'm having to replace them every six months. I would really love just going barefoot, in most situations, hopefully a best-selling book will appear soon so being barefoot almost anywhere starts becoming more widely accepted.