Heavy Weights vs Light Weights

In the higher performance boats I have noticed it certainly pays to be on the light side. 

Generally speaking the rigs are very adjustable and can be depowered upwind.  In addition with light crews they get on the plane at lower wind speeds.  In higher wind speeds they plane faster if lighter. Finally the high performance boats generally have very little rocker which means they drag their transoms easily and don't easily lift them out of the water when trimmed by the bow.

One more thing, in high performance boats the downwid speed is more important to overal postion than with other boats and this is just where the lightwieghts score.  Consequently I'm on a diet.

i think in almost every instance, its much easier to depower, than generate more (legal!) power in your rig and so its better to be light. It does mean that the heavy people can go flat out for longer but the benefits are gained downwind too if you are light. If you're too light, then yes, your performance is hindered but a small proportion lighter than your opposition is usually an advantage.

if its a shifty up and down day, then it generally favours the lighter teams that can keep moving through the lighter patches - in the windy areas, they dont lose as much as the heavier teams do when they are sat in the boat, whilst the light guys are fully powered up.