DVDs or CDs?

One of the questions that came up when talking about delivering Whidbey builds more frequently is distribution medium.  DVDs are a lot more convenient for everyone (and cheaper for us).  Suppose we made these DVD only?  I imagine at certain quality milestones - e.g. an official beta - we'd make cd's available too.  But for an interim build, would not having CDs block many people?  I'm sure we'll find some data somewhere but I'm curious what people think.