Legacy PTQs

A few days ago, Aaron Forsythe suggested the possibility of Legacy PTQs via twitter, following the massive turnout at GP Madrid 2010. The general responses that I saw ranged from “Yes” through “Yes, if you reprint dual lands.” Brian Kibler and I asked the same question, which boils down to:
“Sure, attendance at GP Madrid was huge, but how many people there actually had viable Legacy decks?”
More generally, how many people are actually viable in general going into a Legacy event?
Lino Burgold’s writeup of GP Madrid touches on the experience of playing through earlier-round opponents. I say ‘earlier’ as Lino still had his three byes, so these are people who have one way or another made it undefeated to rounds four and beyond. Consider:
The funny thing about Legacy players I noticed, is that they are a lot more casual than the usual player I expect to meet at a PTQ or even at the weekly draft I do at home. This means they are a lot more narrow-minded about the game in general. They often don