The Champion and K-9 look good in pictures I've seen, but I've never been able to get my hands on one in person to check it out.
I have been told that both of these protectors are "knock offs" of the Honig's K-1. While they all offer a similar design, what I have heard is the "copies" use inferior material and construction. There is quite a price difference between the three!
Again, I have never had any hands-on experience with these protectors. I'm getting this from many previous equipment dicsussions on several different boards.
Here's a link to the K-1:
Honig's K-1