What I hated the most when playing Forza 2 online was when someone was lagging really bad and their car would disappear and reappear infront of you which would, of course, freak you out and make you swerve. Then you're in the grass and your race is pretty much over.

I am pretty sure it'll be the same experience with GT5P and the final GT5 release. There will be lag in online games because internet connections are not up to the speeds of "no lag", yet. Maybe in 5-10 years, connections will be fast enough where an online race would be just as smooth as a campaign race. I can't wait!!!