Warhawk: Buy it on Blu-Ray or download it on the PSN?!?!?

What should I do?! Does it take a lot of HDD space? or not.

Once you download it is yours forever, like if you would to replace your HDD with a better one?

I knowyou can download it using the same account, and on a different system only like 5 times rite?

There is really not much different then? (not counting the headset the $60 comes with)

Is there anything else I need to know if I choose to download it.

FOR THE ONCES WHO DOWNLOAD IT ALREADY: How is Warhawk?!?!?

(P.S. I never bought anything from the PSN store before)

THANKS FOR YOUR COMMENTS EVERYONE AND FOR HELPING ME MAKE A RIGHT CHOICE!