I'm a big fan of all instrumental recordings. But on my years as a concert committee member for a Northern Illinois organization, I was hard pressed to think of many groups that I would vote on to play that was all instrumental. The audience seemed to like a mixture. Even some of the all instrumental performers mentioned above have some engaging between tune stage patter to make the show flow. I know from hanging around some of the hammer dulcimer mafia, that some folks will not buy recordings that have singing on them, but that's a different market.