Back in the day of the Worrell 1000.
The Nacra 6.0's were using the pin head mains.

The Mystere 6.0's were using the first generation squaretop's ripped off from the Tornado sport developed by Booth et al and made by Santonge in montreal.

Hans Meijer's opinion at the time was... the square top was great in the light stuff.. But once you started depowering... the pin head was more efficient because there was less drag up high on the pin head mains.

So... in the point to point race of the worrell... as the breeze came up in the afternoon... the Nacra pin head's got faster and walked on the Mystere 6.0's...

Now... there are probably a 1000 other reasons... but interesting none the less.