GAH. Maybe it was an omen of things to come (I just read Re: Dave and am especially dismayed to hear about cutting his voice out of old shows. Geeawd that would just suck. Royally.)
I don't think they're really cutting Dave out of the archived shows. Mainly just bad sequeing out of the recordings. It would probably be simpler for Webster or someone to create new shows than to edit Dave out of the old ones. The station is just milking the show for as long as they can with Dave's voice for free. In these economic times, I'm sure they believe it's good business.
