Only two Nektar albums were actually done in quad to my knowledge, Remember the Future and Down to Earth. Initially they were Bacillus/Bellaphon lps with SQ logos. There was no stereo version of them released. The story is that when Passport released these titles in the US they were re-encoded as QS/RM to avoid the royalties. But they could very well be unmarked SQs as well. It was my understanding that Recycled was never released as a quad, although the album decodes very nicely. I'd love to find an SQ marked lp of this title if it exists.
Another one that also decodes well is the Passport remix of A Tab in the Ocean which Larry Fast and Mo moore remixed around the time of Recycled. Larry was working with QS systems at the time, although only the first Synergy album is actually quad. However he was well aware of recording using out of phase info, which is probably why these albums decode well.
I always found Journey to the Center of the Eye decoded quite nicely, athough the 5.1 SACD mix is really cool. The lp of Live in NY is taken from the compressed radio broadcast, so doubtful it would decode very well. The remixed cd was taken from the master multi track recording of the show, the sound is superior. There was also a 5.1 SACD version done, it is a good representation of being in the theatre, not super discrete but great for a live surround mix.
The first Bellaphon CD of Remember the Future used the wrong master tapes. When the band was recording the album for SQ quad, they had problems with phase cancellation that obscured the guitar. They shelved the original tape and redid it. Unfortunately Bellaphon pressed the wrong version when they did the first cd issue. It has since been recalled. The later correct versions had a Nektar Approved sticker on them to distinguish them.
Sounds Like This was recorded live in the studio. It is somewhat hit or miss as far as how it decodes, although my Tate makes it sound okay. Again the remastered version on Eclectic has superior sound, as well as an extra disc of outakes and unreleased songs from the sessions.