I had tried the last release candidate before their 1.0 release and frankly it sucked compared to Knoppix...
Add to that...at the time they made the decision to not allow any downloadable version (ie: if you wanted to even try it, you had to buy it) which was fine by me...but I'd never buy it based on what I HAD seen about it.
The problem is that in their forums there was a lot of flaming over the issue (nothing unusual, just the usual net crap) and the staff lost it and basically stated their true regard for the linux community which was basically we were useless geek freeloaders and that Yoper wasn't for us and that we (the community that developped 99% of what Yoper was) was not welcome...
(Up until that post I was pretty much on Yoper's side...but after it, I figured I could never support a company that could issue the statement they issued)
The post itself has since been erased (it generated LOADS of bad publicity for Yoper) but I'm not sure the attitude behind it went away...so I haven't forgiven them. (I'm sure searching this forum you'll find the post quoted...might even have been me hehe...or you can google around a bit).
Basically, why pay a company with that attitude when a better product is available for free? Knoppix at the time was lightyears ahead of it and has only gotten better.