As I understand it, the main differences between casein and whey protein are:
a) Is slowly realised and absorbed by your body over up to 7 hours.
b) Has an anticatabolic affect, which prevents your body from eating into your muscles for energy
a) Very quickly absorbed (within 30 - 60min)
b) Encourages protein growth
If any of these points are incorrect, feel free to point it out!!
Assuming this to be right, I've decided it would be best ONLY to take Whey directly after training (When your body needs a sharp protein boost) and possibly the following morning.
I think on cardio days casein could be better for directly after training because (due to point b) it might stop your body from taking energy from the muscles you're trying to develop on the weight days. ??? ?
This is all prompted by me reading about how doing cardio makes gaining muscle that much harder. Also when I say cardio what I really do is Tabata workouts not standard cardio.