Ok, I would say the medium they are played off is a very important issue, for reasons I have already explained... so I won't go over it again.
Yes, someone did make the point about "everyone being catered for at some stage"... but having read a few of his posts, I find it difficult to set much store by what he says. Besides, one or two token records during an evening is not really catering for enthusiasts of a particular genre, is it?
I tried to put across what I would expect from an across the board night... a reasonable representation of each genre... not just a couple of records.
Regarding your last para., I don't think its really to do with who has the most knowledge of records, but what you say about "the majority rules" concurrs with what I said in an earlier post: The majority want to hear the top 200 oldies plus a few lightweight 70's tunes! That's a pity...IMO.