I agree with Henry. From personal experience the two of my players who took time DMing both became better players after doing so. And there's one thing that we all agree on: Biting the hook. For all those DM's out there, remember the time when you setup some cool stuff to happen, and the players all stayed in their rooms, didn't follow up on jobs, and avoided plot critical NPC's? Well, all the player/dm's that I know (like, all 4 of them) understand that pain, and will more often chase leads or try and deal with people.
Also, since none of us (well, with the exception of my mentor) are all that terriffic, DMing forces players to get used to interacting with things, making decisions, and tracking details. Three things that are VERY important to an enjoyable game.
So in that aspect, players who have some time in the chair are better players.
On the other hand, I'm a bitch of a player. I'm picky (houserules and fun/time ratio). I have a different style. I'm into acting fully (door didn't unlock? Chop it down baby!) and heavily in character. I'm the decision maker and tend to dive in all the way when I dive, and often my group (notably the ones w/o DMing expierence) are the stort that have deep reservations about moving forward ("Ok, I'll chop the door down, but I'd like to do it quietly"). Another aspect of that is that I've never once been able to get a clear answer of what sort of game we're going into and end up with a character who isn't good for the situation.
But you know what? My two stints as a player have made me an infinately better DM. Nothing like playing through two games that are built on the model I introduced to make me see what sucks.