I know a lot of people here like HIIT and I have researched a lot about Low intensity cardio and I have come to like it. For a couple of reasons. First of all, any cardio is good for health benefits etc. Also cardio will help open up capalaries or blood vessels (I could be wrong on these terms) which helps with getting your body more nutrients. This is especially usefull on non lifting days. Due to the increased blood flow and oxygen to the muscles and your body you tend to recover much quicker from your strength training. Also from what I've heard you burn much less calories from low intensity, but a less % of the cals burned comes from muscle. The reason is because low intensity cardio tends to oxidize and mobilize fats rather than actually burn away the muscle and fat.
I know most people here advocate HIIT, but to me HIIT is almost as intense as a real strength workout, and requires you to have more time for recovery. So I figure that it's kinda useless if your hitting your legs enough in your workout splits. Also HIIT really depleates your glycogen and is very catabolic. Your body really starts pumping that cortisol, which decrases test, gh along with many other hormones. Cortisol also eats away at your amino acids during training.
Im sure there might be some errors in my reasoning but I'm wondering what they are. Just trying to start a nice dicussion.