I know a lot of guys who've done it, are doing it, and will be doing it soon. Its really all a matter of your mental fortitude, especially if you get put to work in or near hot zones. The pay is fantastic, and the reality is you can go through 3-4 years of hell and as a result make the rest of your life much much easier and more relaxing. But, the people who've gone won't bullshit you, it can be very tough.