I agree, for me the UK quad mix (on SACD) is the preferable mix of the three. The only small mark against it I think is that a small portion of the guitar solo in Lazy was omitted, presumably to even out the running time between A & B sides on the Q8.
I like the 5.1 DVD-A mix though, it's not 4-corner quad but I don't think it's nearly as front centric as a lot of lesser 5.1 mixes.
I'm not sure why the seller is trying to get so much for that tape - he's been selling Q8's on eBay for more than 10 years and his starting prices have slowly escalated, but nothing like the £3000 he's trying to get for this tape. Presumably he's just hoping someone will message him and offer him a fraction of that price.
I'm not sure if the EMI Q8's were originally shrinkwrapped like that but it definitely isn't in the correct case. I picked up a copy of this tape a few years ago from a seller who was dumping a load of UK tapes in what I believe is the original plastic sleeve, which was like a two part stiff polymer sleeve, where one half slotted in to the other, with the u-shaped cardboard insert and the tape inside.
For anyone looking at buying this, I sold the tape a couple of years ago on eBay for somewhere in the region of $175 to someone in Switzerland I think, and it seemed like a ridiculously high price. Obviously if you're just after the music the UK SACD is the way to go and you can get it for a fraction of the price of the Q8.
Here's a photo I put up on QQ when I originally got the tape that shows the UK Q8 both in and out of the original poly sleeve - note there's still a price tag on the back from a shop called "The Tape Revolution" - this is the UK chain that became the 'Our Price' chain of record shops in 1976 which I think pretty much means you're seeing the original sleeve for this tape.