I took it two years ago. The result is Regular and just half year before that I also took part in TOEFL, and my socre is only 573. So they are the different tests. And my feeling is CAEL maybe focuss on your general capability. It is difficult for you to prepare for it within half year, becase you can't improve your English level a lot within such short period. But it is cheap, compareing to TOEFL. So the suggestion is :
If you think your English is good, and you need a socre soon, go ahead.
Or
Go to TOEFl with three months full time preparation, you will achieve your goal.