I've been doing CrossFit in some incarnation for the past 6 years. It's good stuff. I regularly switch to a strength focus for 2-3 months at a time, but always maintain some of the metcon workouts in my arsenal. I'm currently off of CrossFit completely due to sprint training for a track meet in July, but will resume CF when that's done. I like Kevin's ramp up on the SimpleFit program, something that CrossFit doesn't specifically lay out other than to say "scale to your needs."
Don't get me started on The Zone...been there, done that. It's good, but a bit anal. Yes, to be the very elite, having an understanding of your food intake is important. The Zone is a great starting point to understanding intake, serving sizes, etc. Yet, a clean Paleo diet seems to get most people to the 95% mark. So how much time and effort is it worth to shave 10 seconds off of Fran? I'd much rather not have to be so anal about my diet. There's also the fact that the elite CrossFitters aren't doing the Zone. They have ramped up the fat to the point that the ratios are quite far from 40-30-30. It's a Zone in principle only; basically it's become just a way to measure intake.