I just purchased some 535's the other day. I've owned a previous pair that crapped out on me last week because they fell out and when I put them back in a bunch of sweat damaged them.
I'm meeting an audiologist tomorrow to get a mold of my ear canal for custom iems. He's going to give a bunch of options, Sensaphonics, local molders and a variety of materials and I'm finding it hard to get some information on the internet.
Also, what would one recommend for someone who uses these primarily for jogging (indoor track of course) and weight lifting? If anyone knows of any articles that talk about this a link would be great too.