To be honest, I found CF to be effective when I was still training BJJ. I actually am of the belief that CrossFit is about as effective as it gets for combat sports of any kind unless you're A) Undersized for your weight class and don't/can't cut the weight to drop a weight class) B) Trying to put weight on, in which case you'd have to change approaches and diet.
CF, at least for me, is perfect as I can cross train my sport as well as my strength and conditioning. Remember that CF is a mix of ME and metcon with a large number of core-centric exercises, and mixed medium to long distance efforts.
And if you don't think kettleball squat cleans are difficult, I say, step up to the med-ball
- CJ Kim