How do you feel about Yogun Fruz?

I have a confession. I am OBSESSED with frozen yogurt. I love 'em all; strawberry, mint chocolate chip, mixed berries, etc. My problem with this is that I don't know how many times a week I should be consuming it without gaining weight. What about the sugar-free options? Are they better than the ones with the sugar added or worse because they aren't "real" foods?