Like Martin, I was at one of these three shows. It was brilliant. It has left a legacy in that Relayer has always been my favourite Yes album and 'Gates' my favourite track.
I don't remember which of the three nights I was at, but it was a marvellous concert. I was a student at Sussex University in Brighton, and I hitched back after the concert. The reason it sticks in my mind so clearly is because I was given a lift back to Brighton by Roger Dean...!