We are making the switch starting with the next batch.
Why the switch and why did we use ABS to begin with? Firstly we used ABS because we do think it is a good material (its been used in industries for years for tough parts..including car parts and football helmets). Many people think it was chosen due to the lower cost/availability but this only affects sheath prices like $1-3 each so it wasn't a deciding factor when I went with ABS. Furthermore neither material is available to us here so I have to import either from the US. The reason I went with ABS originally was because it seems to handle higher heats better, and the finish has a bit more shine. Either material will deform if it gets hot enough, but Kydex deforms easier...which is one of the main reasons sheath makers prefer it over ABS...its easier to mold.
So why are we switching now? Colors.
ABS is only readily available in black or white. Kydex is available in many colors. I'm getting a bit bored with black all the time and thought I would add a splash of color. It made more sense to phase out the ABS and just switch to Kydex for all colors. Now while Kydex doesn't handle heat as well it is a bit tougher, and since it deforms easier with heat it will have slightly more crisp lines when molded. Plus its easier for us to mold, and many people like the more matte finish it has.
We will be rolling out the new sheaths in March.