I have been looking at these cases for my external or bare hard drives, & would use the firewire with the firewire port on my 2010 i7 macbook pro, the case comes in 2 types, firewire 400 & usb, & firewire 800 with usb. Which one should I get? the firewire 400 is cheaper, would it work with my mac's firewire port? is firewire 800 alot faster? if I got 800, would it work with the ma'c firewire port? I am a bit new to fire wire, has anybody used these cases? are they good?