RE: Bic Techno Formula 170
I would say go ahead and make a purchase for light winds, because it's nice to be able to get out on the water instead of waiting for enough wind for a freestyle shortboard.
If you don't think you'll race, it probably doesn't matter whether you get the F160 tufskin or the Techno Formula. I doubt there is much difference in how soon they plane or how much fun they are. But if you're going to race, the F160 has better speed, angle to the wind, and control.
You could also consider lightwind planing boards that double as beginner boards, like the Rio or Phantom. That would be nice for your friends.
Or if you don't already have a longboard, the new ones from Exocet are fun and plane earlier than old longboards.