On Amazon I only list Digirig in the default config (logic levels) and only the cables that work with that configuration. For CAT functionality with Elecraft KX you’ll need Digirig in RS-232 configuration. You can change the configuration at home, this involves cutting existing traces and bridging the pads with the solder blobs. More info here:
You can easily modify logic levels configuration to TX-500 (just one solder bridge, no cutting). With your HT you can use Digirig in any configuration.
If you plan to use both QRP radios with CAT control, I’d go with separate Digirigs in different configurations clearly labeled. You can share the same Digirig between the two if you use CAT with one radio, but not the other.