I routinely stop eating at 7:00 pm and then have my first meal at 7:00 am before I head to the gym at 7:30 am. This is not an attempt to do IF, it's just my natural rhythm, but it does turn out to be a 12 hour window. I have not tried MAG-10.
Lifestyle-wise, I would have a very hard time extending this beyond 12 hours because I train early in the morning, and because it's important to me that I sit down and eat with the hubs and kids at about 6:30 pm every night. I fall more in the fine tuning group anyway, rather than the "has a lot of fat to loose" group.
Just a note for people who are interested in IF in women specifically. Search Paleo for Women "Shattering the Myth of Fasting for Women: A Review of Female-Specific Responses to Fasting in the Literature." The gist is that women tend to have more trouble with IF and calorie restriction than men, with more incidence of hormone disruption and metabolic slow down. I've talked about this before, but women also seem to have more trouble with carb restriction than men, and need to watch for signs of depression on low-carb diets.