I got a set about 5 months ago. I did have to get them replaced 1 month in, but not due to sweat problems. Something inside one of the ear pieces started to rattle, and they replaced it for me.
I run with mine every other day, and I do sweat quite a bit on those runs. I've ruined several other pairs of wired headphones, and saw the Jaybird advertise as sweat proof, so I decided to try them. And while I really can't compare them to many other "sweat proof" headphones, I can say that I believe these live up to their claim.