You are not going to burn more fat by doing HIIT than if you would not and just eat less, so you get the same caloric deficit.
However, there are some benefits with burning more calories so you can eat more calories at the same deficit, 1) being able to train harder and (hopefully) still progress, 2) more calories while cutting maintains muscle mass better.
Yes, I know... but I am very hectic with all this, really... I do, more or less, what I feel like doing depending on my mood and the time of the year I am in... Summer here is burning hell so I try to go as short as possible while working out, so HIIT is great... then I discovered that it is what I really like for cardio (except for swimming I hate, truly, all "convencional" forms of cardio... running, eliptical machines, steps/stairs, cycling... I get bored to death and end up quiting because of it, and they take too much time of my schedule).
Reading you guys and some other forums on this matter I know I am completely anarchick in my training and my eating but it seems to work for me... don't know, maybe good genetics or something...