Derek,
Yes, the credits thing is strange indeed. I was sure there was remix credit on the quad Peach release until I recently purchased a copy and saw that I wasn't mentioned. The more odd thing is that I did get remix credit on the stereo CD release of Peach, and so did my assistant, Debra. My guess is that the CD was a down-mixed version of the quad mixes so that's why the credits appeared there.
Kinda sounds like a remastered, and unfortunately, re-EQ'd, version of the quad mixes to me. Sadly it sounds like the mastering engineer thought the vocals were undermixed so he EQ'd that region of the spectrum up to compensate. The vocals were slightly undermixed but that was intentional as the ABB was known primarily a jam band and for the great guitar work of Duane & Dickey. The vocals, while soulful, weren't always right on key or as powerful as the music.
I've had the CD for a long time, with mixing credit, so I assumed the credits were there on the quad release too, but not so. Oh well, my online discography contains projects I don't think I worked on at all and then there are some that I worked my a** off on don't show up at all. Such is life...
And, no, to your last question - these would definitely have been the only two quad albums I would have been involved with. Wish it had been more because it was really a lot of fun to mix in quad! I may have mentioned that we had a Tom Hidley designed & purpose built quad control room with superb gear, some of the best available at the time. It was a privilege to get the opportunity to work in that environment.
Best,