I went to ATP jacksonville in early May and was pleased with the results. I came as a 800hr single engine CFI/II and left as a com multi with almost 50 hrs multi time and it only set me back $4K. I returned to the flight school where I work and quickly knocked out my MEI having enough time to meet our insurance company's minimums for renting/teaching (500TT, 50 mulit, 10 make/model).
The training is accelerated and takes a lot of self-study motivation. I took my mulit comm add on with just 8 hrs in the mulit. The rest of the time was aquired doing what they call an ASAP program. I basically ferried their planes around the SE. I was back home teaching in Denver after just 8 days! They'll fly you hard (up to 9 or 10 hrs a day) but they do a good job living up to their promises.