Even if he has been in radio longer, Glenn Beck was made for TV. He is really developing a large and loyal following on Fox news. I always thought his radio show was good but it didn't really stand out. On TV he is a star and a real entertainer. Maybe it's the emotions and passion he shows on camera, but TV is the perfect medium for him.
When it comes to conservative talk radio Rush is the best. As someone who enjoys right wing radio I find Rush's show to be extremely interesting and entertaining. He makes many other conservative talk shows seem dull in comparison. So even if Glenn Beck has name recognition and rising star power, my guess is that he won't make much of a ratings dent against Rush on KXNT. Now if Glenn's show happened to be on at any other time I think he would be much more competitive.
At the same time I can understand what KDWN was thinking by dropping Dr Laura. It's the reason why many talk stations dumped her earlier this decade. It's too inconsistent and different from the rest of the stations lineup. Talk listeners generally want to hear talk about news and current events. (and Dr Laura fans would probably not be interested in political talk). It would be like a music station airing a block of a different music format for 3 hour each day. Perhaps someone should invent an advise/lifestyle, more female targeted talk format, Dr Laura would be the perfect anchor for it.