And what about the Sails? How "Standard" are they? As Karl points out, you get the right sail on the right mast, you have something...wrong sail, wrong mast (settings, bend, etc.) and now you're "slow". I know I've got two spinnakers, a slow one and a fast one. But they are by two different manufacturers, so you would expect there to be differences.

I know nothing of building sails, I'm sure the panels are cut by a computer, but are they then sewn/glued together by hand? And what are the tollerances when they are doing that?

No matter what you are building (boats, sails, etc.) there are going to be very small variances. I know some of the serious Laser racers are freaks when it comes to "Picking" a boat, they measure a bunch of hulls, weigh them, flex them etc, same with their masts, sails and blades. They want the lightest, stiffest stuff they can get... and then they buy a new one every year, as their old one is "worn out".