Are loose footed sails more powerful?

In the Y&Y piece about National 12s in the last edition there was a statement about the change to loose footed sails and it making the rig more powerful offwind.

Is this really true? and if so does it affect more than just a 30cm band along the boom on a tracked sail?

I'm thinking of buying a loose footed sail but keeping my tracked boom so I don't have to re-cut my 'practice' sails. At 14 stone sailing on a lake I lack power on a reach and it may sway my decision to go for loose footed if it gave me some more power.

Matt, I think what they are referring to might be the extra area you get from the foot round on a loose-footed sail, not anything to do with the depth of the sail at the foot or not being able to ease the outhaul enough.

I've never sailed a boat with a tracked footed main and gone down a reach thinking, "Damn, if only I could ease this outhaul a bit more, then life would be great!"  You can ease off the outhaul as much as you like on either type of main.

Wheras a main with its foot in the track will not be able to extend below the boom, with a loose-footed sail you will get say 30cm of foot round which will sort of fold itself up against the boom when the outhaul is on, but will drop down and set when you ease the outhaul.

So you get a little bit of extra area, but I'd be very sceptical of exactly how useful it is down there below the boom. Still, it's probably worth having, and a loose-footed main is easier to build than one with a soft shelf foot and boltrope, so you might save a couple of quid too.