Well, I've only made one Skill Swap team ever--my current team--and don't usually run into them, but it seems that they're useful so long as you don't try some overly complicated Skill Swap chain and if you use it to screw over the opponent (stealing Dry Skin from Toxicroak on a RD team, taking away Bronzong's or Gengar's Levitate right before the opponent EQs, snatching an Intimidate from the opponent and weakening them, that sort of thing).
EDIT: Oh, and also, I'm more comfortable with 6v6, although I suppose that's because I rarely get a chance to play the other.