I guess it comes down to...if u dont need it or need it, if u have enough in outs then you don't need anymore peripherals, if you find your self with too many sources and not enough in outs then you probably would need a mixer. I think the 002 should be enough.
Well now....if ur friend was talkn bout a dj mixer....i just thought of that rite now... Then i guess u should get a dj mixer because it makes using turn tables easier and entertaining like cross fading n ish. The two turntables well go into the in's of the dj mixer and the output of the dj mixer will go into ur 002.