As far as I know only audience tapes circulate. I don't recall the "strange atmosphere" you are referring to, but bad discs abound. Here is a review:
Frankfurt 9/30/73 1st show; 75 min; 6.5 m; "Frankfurt Tapes 1973"
Frankfurt 9/30/73 2nd show; 75 min; 6.5 m; "Frankfurt Tapes 1973"
Both shows are available in a 2CD box. Each is a pretty good audience
recording. Mick Taylor is quite loud here, especially in the 2nd show.
Plus there is a video of (I believe) the second performance SFM--[
www.micktaylor.net]