Actually I have two complaints about the Retro-gression straps. I personally feel that they are a bit too smooth; when I put my feet into the straps, they don't feel as secure as I would like them to be. They do, of course, hold my feet in well, but it just doesn't feel secure. Also, I think the velcro straps (the double-sided ones) are too long. I had to cut them down and strap them to the very end in order to get a decent fit.

For those reasons I'm looking towards buying cages now.