Anecdotally? I would. Could I accept being proven wrong on this statistically? Sure. But 8.5 rounds of golf seems to be more stable than 5.Who among the top players would be favored higher in 8.5 rounds versus 5? In other words, would you rank players' odds of winning in 5 rounds different from your ranking for 8.5 rounds?
That doesn't even take into account that we seem pretty standardized, at that level, at 18 holes per round now. I'm kinda irked I can't seem to see the layouts used for old worlds.. but, for example, were there not 24 hole layouts for 2008 Worlds in Michigan? So we're not only talking about a world where we're playing fewer rounds, but we're also now locked in to no longer using 24 hole layouts.
(if additional holes weren't used for Pro Worlds in earlier years, excuse my mistake, but based on courses used - I assume there were)