That fits my assessment too.
The Yes Album is definitely the earliest that we can actually
hear him in stereo (at least on "Starship Trooper" and "Perpetual Change," although to the best of my knowledge/observation he - or Eddie rather - never panned the channels out separately like that again - I'm not counting the stereo effects like the Harmoniser later, just the obvious panning of neck & bridge pickups). And somewhere I have read that "Trooper" was recorded on the 21-fretter, but I've never seen any hard factual confirmation of that. But given the timeline - RM headstock breaks (again), Sam Li fixes/shaves off silver stuff/refinishes in cream, CS does shows with 21-fretter and at least two Dual Showmans (Dual Showmen?) as pictured on
TYA sleeve, "plays" both the 21-fretter and the Tele Bass in the
Time And A Word Belgian clips, has RM back in action certainly no later than the Beat Club/Musikladen "YIND"/"All Good People" clips around January '71, where he has two coily cords visually evident (going to the same channel of one Dual Showman!) - I wouldn't be at all surprised if the 21-fretter a.) inspired the stereo change to the RM; and/or b.) was used on a lot more the
TYA than is commonly known/accepted.
Now, if someone can track his effects and amp changes over the same period,
then we'd be in real business!
(Okay, I'll start - wah on "Survival" in the studio, but not on Beat Club/Musikladen; Marshall Supa Fuzz
all over the "long" version of "For Everyone" and then audibly evident on
TYA ("YIND" and "Trooper"); tremolo - possibly from the amps - on "Trooper"; CS's live rig at Crystal Palace in June '71 includes the Mister Bassman bass pedals, the Supa Fuzz, and a reverb/tremolo amp switch (all are audible at some point on "It's Love", especially the version on
The Word Is Live); the wah is back on
Fragile along with trem and fuzz and the kitchen sink available at the time, especially on "The Fish";
Fragile tour, the wah appears for "The Fish" as so adroitly displayed on the
Yessongs album version, with what still sounds like the Supa Fuzz, Mister Bassman, and tremolo - amp or pedal? who knows? who cares? obviously me; the first appearance of the remote relay-type switching on the
CttE tour with Alan as seen in the
Yessongs film, along with the first confirmed sighting of the Maestro Bass Brassmaster (on top of the Sunn Coliseum Lead head), which I
think is first heard on record on "America," but it might be somewhere on
CttE, or it could be amp distortion or the Guild fretless or something else - and now I'm petering out - someone else, do the amps,
please....

)
And I hope you haven't been unhappy and not sleeping this whole time, Gunnar! (Nothing like reviving an almost-year-old thread....)