Reply to Traktor F1: will one suffice or....

I'm considering getting an F1 to add to my Traktor S4, but in all the promo vids the performers are using two F1's. So I'm left wondering if only having one would be worth it since I'll only have control over 4 remix/sample decks. Or do I need two of these for it to be worth it

Other options I'm wondering about, in place of the F1:
1 - would a MidiFighter (of any flavor) be better if I'm only getting one device?

2 - would TouchOSC or Lemur (I hear a Lemur mapping for Traktor 2.5 is coming) do the trick?

2.1 - Does anyone know of a good mapping for TouchOSC so I don't have to reinvent the wheel with this?