That's a shame, I remember that expectations were primed for some significant finds in Durrie Parks' collection. And yet, out of nowhere we get this WH-era SU performance. Archival work is odd that way - revelations often surface where (and when) you least expect them.
You mean, in the tape vaults themselves?

Actually, yeah! There was a presumption that most of the material was already 'known' and documented. There were also the 'known unknowns'...like the SU session for the second movement etc. But the '67 SU is definitely an 'unknown unknown', which flew in outta left field.
I wonder how The Elements will be handled in the booklet? The Psycodelic Sounds stuff has always sounded like sketches for a fully worked-up version - I wonder how ML and AB resisted the lure of attempting an Elements suite mix? One for the fan mixes, presumably.
No offence, but it just sounds like Brian dicking about with his mates.
Why record it, then? I don't know, but Brian would surely demo any potential BB's material with them, and did - the off-mic piano and vox exercise, for instance, never made it further than that, as well as other fragments - but if the psychedelic sounds tape was anything but Brian goofing about we would have BB's equivalent. Maybe all that came out of it was the Water Chant, but I don't know the dates.
None taken, that's an operating assumption on all of the Vosse Posse material really. But there was a serious side to that 'humour', gawdawful tho much of it was. Those tapes were a bit of a laboratory I think, testing things out, but also improvising material, then weeding (har) out the (majority) stuff that wasn't useable before bringing those ideas to the BBs. Vega-tables seems to have evolved that way, Water Chant certainly...so my speculation is about the other 'elemental' tracks.
IIGS and Barnyard are also intriguing to think about in this context, because the musique concrete and humour motifs are pretty strong on these ones, and much of the humour material that was excised from H&V may have wound up here at some point. It might be that some goofy or experimental bit was rehearsed here - the echoplexed basketball game seems to have surfaced, however briefly (insofar as there is, erm, echoplex feedback present) on IIGS.