I have done the same in a more informal setting - 90min talks on various aspects. I did one using only recorded items - the other two mixed my singing with recorded items. A number of the regular audience said they preferred the mix. I haven't dared try them with only my singing - Anne tells me that would be boring.

Live performance makes it easier to illustrate variations - alternative words, tunes, etc.

Live performance involves the audience more effectively. I know that I have enjoyed many unusual classical works in the concert hall which I would probably have turned off on radio. Seeing the performer in action makes a big difference and probably outweighs the possibly lower quality of the performance - a matter of taste, anyway.

Phil