The quad mix is fake, sadly - I did a bit of a
breakdown/analysis of it in 2019. Finding out was a bitter disappointment for me, because the other Herbie quad mixes are great and it's an album I love, and also because I paid a small fortune to get one of the handful of Q8 tapes that ever showed up on eBay to find out.
A better option would be if Sony would like Michael Dutton remix the non-quad Herbie albums like Man-Child, Secrets, Sunlight, etc. in spatial audio and release those mixes either on Blu-Ray or downmixed to 5.1 for SACD.