Various games run under a co-headwiz system. In my opinion that's a great idea and something I do as well on my games. The reason are many but to me the best reason is RL. As I've posted in other locations I spent about a month in the hospital last year but I didn't worry about the game because I had a co-headwiz I trusted to do what needed to be done. If the game went down I knew they'd be able to start it back up.
The catch to the co-headwiz(s) is who has final say. For the most part I would never have a co-headwiz who didn't agree with the basic concepts I see in a game. And there have been times we've disagreed with how things should be done. But we manage to sit down like two adults and discuss it until we come to an agreement. Just having someone to bounce ideas off of before I go and do something is a great resource in itself and has prevented me from shooting myself in the foot several times. Normally when I do something as a knee-jerk reaction without talking to someone is when I screw up.
On the flipside if you do decide to have a co-headwiz(s) I can not stress how important it is to make sure that you both have the same basic philosophies on admin, gaming, etc. The last thing you need is a headwiz who disagrees with everything you do cause that's what marriage is for ;).