Think about it, theres a reason the two major schools of weight loss are low fat OR low carb
I always thought it was because the low protein option was an obviously bad one. Then again there are vegans...
Truth be told many of the newer, more popular diets aren't low fat or low carb but instead they focus on moderation of both. Iso caloric diets are not low fat, nor are they high fat. Same goes for the carb intake, yet I think a great many people on this board follow something along these lines. 40/40/20, 40/30/30, etc... are all very close to iso caloric ratios and most people have great results on them.
Unless you're in the extremely low bodyfat %'s looking for every possible way in stripping the last bit of fat then I think the combinations of fat and carbs that I listed above won't make or break your diet. I'm guessing most of us that are actually worried about the f + c mixing aren't down this far yet.
You can only lose fat so quickly before you risk muscle loss and extreme metabolic suppression. If you can manage to reach that level without resorting to extreme measures then why would you do so anyways? If I can burn 2-3 pounds of fat per week eating smaller amounts of fats and carbs together then why on earth would I want suddenly stop doing it in hopes of more fat loss when it simply can't get any faster? When the time comes and I hit a plateau then I can look for other alternatives, this one being a possible one.
One last thing. I'm not sure who "officially" started the p/c/f mixing phenomenon as I know there is more than one person promoting it. However the first time I, and probably most of you, were exposed to it was from John Berardi at T-mag. However what a lot of you probably don't know is that John came back in a later article and said most people were taking his recommendations to unnecessary extremes and that mixing c + f in moderation was not a bad thing(so long as protein was <b>always</b> included in the meals). I'll try to scour T-mag for the link and hopefully some of you obsessive/compulsives can rest easier tonight knowing that the 3g of carbs in your protein/flax oil shake didn't blow your diet.