If there is a HIIT sticky, please hook me up with a link. I didn't see one but maybe it is buried in one of those threads??
As for my goal, I have been on a BFFM style "diet" for 7 months, successfully losing fat while maintaining muscle (even gaining some) and want to continue this until I get down to a single digit body fat %. I started at 30% and am now at around 17%. My original goal was to do this by Christmas and I am currently somewhat ahead of schedule.
As for the calorie thing, I am not familiar with the term "metabolic target" and am not sure where I can find a definition for that. Does this mean aiming for a higher basal metabolic rate? That is what I had thought HIIT was for. This would in effect burn more calories over the course of a day although you would be burning most of them at rest rather than during the workout.
I am currently burning 500 cals in my cardio workout and so wanted to at least match this with HIIT. Although I may do the same percentage caloric deficit with or without cardio, that same percentage deficit will obviously be more when cardio is a part of my routine since my TDEE will be higher. And a deficit of more calories means I will lose more fat. So this is my current reason for doing cardio. If HIIT can't burn an extra 500 cals in a day for me, then it doesn't seem like an activity that aligns with my goals.