Concerning "The Dean"... I am afraid this might turn out to be a mistake like "Unknown Balad" on ELP's Tarkus remix, where SW found an unknown piece of music on a master reel and thought it was an ELP recording (which it wasn't).
The Dean sounds nothing like Yes in that period. The singing is definitely not Jon Anderson's or Chris Squire's or even Steve Howe's vocals. Perhaps they let Rick or Bill have a go at the mic, but i seriously doubt that
. The drums don't sound like Bruford's playing either.
I wonder what it actually is, but if it really is Yes, I understand why they never developed it further. My bet is it is not Yes, but some other recording that was found on the reels.
Curious...