2 socks on the ML: toe up? or cuff down?

[itsjustmeghan]

i've figured out how to do socks on the ML. now i'm thinking about figuring out how to do 2 socks at once. just makes sense because i won't have to go back and finish that dreaded second sock!
i've always done cuff down socks, but i figure since i'm teaching myself something new, i might as well open the door to knitting socks toe up if that's easier with 2.

so, on the magic loop, when you do 2 socks at once, which way do you do it? toe up? or cuff down?
and please explain the benefits of one or another.