I stand corrected, but the Kyocera printers that support KPDL supports Postscript as well. (If one sends a postscript file to the printer when it is in KPDL mode, it gets printed correctly)
The number of prints one gets on a cartridge is much higher than any other brand. I get on a TK-20H cartridge (US$100) using an FS-6700 printer with a mixture of A3 and A4 I get 23000 to 25000 prints per cartridge. The A3 prints are mostly mechanical drawings and schematics, while the A4 are typical technical documents such as user manuals etc.
The drum which Kyocera rated at 300000 prints needed replacement after about 250000 prints. The quality of the paper we can get is fairly low, so I expect if one used better quality paper one would easily get the 300000 prints stated life.
Regards Anton Erasmus