I just spent the past few hours converting the C&C PCs from my Saturday group over to 4e. I want to see if this deals with my own boredom with "Old School Dungeon Crawling" (because, honestly, there's just not a lot for my goblins to do most of the time except make me roll a lot of dice and die horribly), and addresses the concerns I had with the tortoise-like rate of advancement that is Castles & Crusades. While this will mean a bit more work on the game prep front, I'm hoping the payoff will be a more engaged DM and players who still have fun.
Also, two of my crew are moving away at the end of the summer. I figure if I teach them how to play 4e, they'll have a little better shot at scaring up a new game if they decide they want to keep playing in their new city.
But until game time, I'm going to be wondering if it's the right way to go. I know the world won't end if it's the wrong choice. Granted, according to some, the world will end on Saturday. I guess any game is better than none under the circumstances.