I posted this response in another thread, but I thought it might be good to share here, too.
This is a seriously old post so I don't know if anyone will read this, but I thought I'd share my experience. I enrolled in a debt management program in November 2011. My FICO was 577 at the time and my utilization rate was 95% (maxed out). My score did not drop because of my enrollment in the debt management plan, but when my credit report is pulled, it does show that my cards are being managed by a CCCS. Because my interest rates are so much lower now (dropped from an average of 22% to an average of 4%), I can pay off my principal owed much, much faster and even though I now pay less every month on my credit card bills, I have dropped from 95% util in Nov 11 to 78% in Aug 12. My scores have climbed from 577 to 644 in the same time period.
One more note - although you are not allowed to incur any additional unsecured debt (credit cards and such) you can get secured credit (like auto loans) while on a DMP. I got a car loan in February 2012, less than three months after enrolling in the DMP. Not all lenders would agree to work with me and several said they see the DMP as a red flag, but I had a fairly long credit history (oldest account was 10 years) and average age of account was 5 years, with no new credit or inquiries for over 2 years. I also had a mostly good payment record, with only two 30 day late payments ever. I used the good parts of my credit history to argue that I was responsible and making a good faith effort to pay all of my obligations. My debt to income ratio was also pretty good so I could demonstrate good ability to pay to new car loan. I didn't even have to pay a terribly crazy interest rate.
I would also agree that it is essential to check all of your credit card statements every month to make sure the appropriate payments are posting.
Starting Score: 577