I know the KL1 is supposed to be a "drop-in" for the E-series. The digital part I'm not sure of.
AFAIK, the straight digital lights have different bezel and cap threads from their "analog" counterparts to assure that the lights work properly. I've read that the E-series lights with the KL1 won't have the two-stage digital switching, apparently because of the lack of the digital circuitry, so this leads me to believe that the only digital lights are the ones specifically made to be digital.
Then again, I read one reference that the KL1 bezel is so much longer than the standard E bezel because of "digital-itis".
Hmmm, based on both statements, then, maybe it'll be digitally controlled, but without the digital two-stage switch.
I feel that the KL1 with an E-series light would be a great combo, regardless of digital control or not.