It seems to me that the core of this discussion is extremely subjective. I might frame it as a difference of opinion/perception in terms of "do the highs compensate for the lows?", which reflects my priority of tight musicianship. But a deadhead would never ask this question because from their perspective, there are no highs without lows-- the two figure equally in the overall gestalt. I’ve encountered deadheads who fervently believe that consistently tight musicianship = "soulless professionalism".
Frankly, I don’t see much common ground here for debate. I will never grok the "ragged is right" ethos" but I don’t have to in order to enjoy my favorite Dead recordings.
Another difference appears to be that deadheads belive when the Dead played at their best they reached a level unmatched by other bands, which in some way justified the Dead's off nights. I simply don't experience this as accurate. The Dead at their best were wonderful. But not more so than the original Allman Bros., The Who or countless others. Again, there is a fundamental difference of perception that from my perspective, cannot be bridged.

