Received in December 2009, 20 € on thomann, used non-stop since my Epiphone Thunderbird (bass heavy and itchy nose). I had straps in cotton Levi's (the classic) and a Fender Leatherette (comfort). The locking system is very well thought out. No problem, it's yours and it seems durable. The inner side is as stated above in a plastic unknown a little soft which does not scratch the varnish. Cons by the strap seems among other nylon. This makes it very smooth. If you have a Jazz bass or a guitar that will do nothing, but with Thunderbird (or crawl) like mine, she replies with less resistance to abrasion on his shoulder, so that the lower slip. Otherwise, 5cm wide strap as a standard. I'll add an epaulet (species of stuff on sports bags with foam and grip), so the problem of comfort and nose picking future solved! =)
I was fortunate to have a strap of a bag formerly used black sports go, otherwise you can see for this kind of thing:
http://www.musik-produktiv.fr/planet-waves-pw-fsp-1.aspx
In short, the solution to have a free mind and no longer see his guitar to kiss the ground without him tamper fasteners to put strap-locks ...