The problem is that the original Knight keyboards and first coupla generations of LispM keyboards were made with full mechanical Hall-effect switches by Microsw

The problem is that the original Knight keyboards and first coupla generations of LispM keyboards were made with full mechanical Hall-effect switches by Microswitch, a Honeywell subsidiary. There were never more wonderful keys crafted by the hand of men. Sadly, once Microswitch stopped making these, even on a custom basis (they lived on for a long time as ATM keys, etc., since they were certified for millions of up/down cycles), that particular silken feel has been lost. I still have my 3rd generation LLNL Microswitch keyboard, commissioned by the MIT/Stanford folks working on the S1 supercomputer. Even this 3rd generation can't match the original Knight keyboard feel. Sigh.