Apologies for double post - the £17 price is for qobuz "sublime" subscribers. Usually about £45 for hi-res stereo download. Might still be tempted, though...
I didn't know of the existence of the 6-CD set until you posted this. I have both the original set (on Mobile Fidelity gold CDs) and the expanded "Fillmore Concerts" from 1992, either of which is essential. At the time I bought the 1992 set, observers noted that added horns screwed up some of the recordings by playing slightly off key. Therefore, most takes with horns were excluded from the original and expanded sets. These discarded performances are obviously included among the 6-CD set.
Therefore, I would warn that some of the horns may be intrusive and/or off key. As I am intimately familiar with the original and first expanded set, I can also attest that 6 CDs may be too much of a good thing. They played virtually identical sets at all the recorded shows, meaning you're going to get three Elizabeth Reeds, three Whipping Posts, etc., and the repetition may get tiresome. Finally, although I find Duane Allman's playing endlessly fascinating, Dickey Betts' more limited approach has worn out its welcome to my ears.