I think that FattyFattyBonBon's comment that better than 50% of the racing occurs at less than 6 knots really makes the case for use of a second board (Serenity), as Aco has advocated. Really, a great idea.
The two board solution could mix outcomes favoring light versus heavy sailors depending on wind strengths during racing, but it just might benefit the medium weight sailor overall, especially if the mixture of athletic and tactical strengths and skills were keenly developed. Also I think, the modest sized OD sail would tend to balance things more towards the center.
But there's no getting around the fact that the wind conditions could ultimately influence outcomes. I guess things really depend on how many races are run over a period of time to determine the medal outcome. But, the Olympic moment(s) is one of the classic features of the games. You got to be able to do it all in the conditions and timeframe specified. Although a given sailor might be the best rated sailor in the lightest of winds, that sailor may not come out on top if all the racing is run in strong winds. A victim of circumstances? Yes, that could be rationalized, but I doubt that it would find traction in the Olympic arena.
Lastly, concerning FattyFattyBonBon's reservations about how changing the equipment could ultimately disadvantage RS:X sailors, it must be remembered that the next Olympics is 4 years away in 2012. In my mind, that's a considerable period of time to develop and hone the needed skills. In reality, I wonder if the Olympic competitors from 2004 feel shortchanged with the introduction of the RS:X, but does it really matter? Furthermore, the idea that a competitor should be able to come back and compete in multiple Olympics over time, shouldn't be rooted in a unchanging world, but rather one that like real life, where change is a paramount factor that we all have to deal with and hopefully thrive.