We've discussed this a little bit on a couple of occasions. It's cool that they made the sheath to work with a 5 or 6, but a knife-specific sheath with retention would be cool. Especially one that could be worn on the belt if the user desired.
Gulp, I just got some kydex from knifekits last night. Whenever some time frees up, I'm going to make a sheath for my 3 and 4 that will work with the kit. Along the same lines as what comes with the kit, but with molding for retention. We'll see how it goes. I will probably nix the sharpener loop and just use Ranger bands. The only issues I've had with my kit is the sharpener popping the zipper, but I fixed that in my sharpener mod thread that I did.
I've mentioned it before, but I'd like to get an aluminum pin with a cotter key or something and replace the Chicago screw that comes with the kit so I can quick change the sheath from 3 or 4 to 6.