I did SN2ed's MCAT prep (the 3 month version), and I cannot possibly imagine having any time to take a class. I spent at least 8 hours a day on that and was totally fried by the end of the day...if you're really committing to the MCAT prep like I did then I would say just study and keep auditing. You don't want to have to take the MCAT twice, do it right the first time.