Links please, if you have any.
I implanted switch parts from various sources¹ into a late-80's G80-1000, a late-2000's G80-1800 and an early-90's 5191. I did the test² repeatedly with various keycaps too. (Several other people (non-enthusiasts) were asked to do brief ABX testing as well.)
Nothing stood out in terms of smoothness, except the 80's G80 MX Black housing+stem (and old/used brown stems, but I don't know enough to make any conclusions from that and it's not the point here); even blacks from the Wyse keyboards would require Cherry picking (pun not intended), not to start with old blues (or their housings, respectively).
I should start a thread with all the details… some day.
¹ MX Black from mid-to-late-80's Cherry G80s in NIB to newish condition, late-80's/early-90's Wyse terminal keyboards in newish to heavily-used condition, a late-2000's heavily used Cherry G80 (to the point of inconsistently shiny PBT keycaps), and early-2010's slightly used gaming keyboards (QFR, choc mini) and NIB switches (Massdrop); I also tested MX Blue from late-80's/early-90's 5191s in NIB and heavily-used condition and from WASD (bought in 2012/2013, never used), and MX Brown from an 1996 heavily-used G80-11802 and a NIB 2012 Kinesis Advantage
² puzzle games played on ASDF remapped to arrows
