Can PPIII be matched? I think that comes down to how much the individual concertgoer enjoys the respective bands on a given bill. For me, PPII was vastly superior to PPIII. I love Symphony X, Ark, Evergrey, Kamelot and Angel Dust. Additionally, I would say that I prefer each of those bands to all of the bands at PPIII, with the possible exception of Zero Hour.
If I was a betting man, I would bet that the following bands will be present at PPIV:
Iced Earth
Evergrey
Symphony X
Vanden Plas
Pagan's Mind
Power of Omens
Keep in mind; these aren't the bands that I'm hoping for (though I would LOVE this line up). Rather, these are the bands that I believe will be there, based on conversations I've had with various people (no, I don't have any inside information). If this is the line up, I would say that it's also vastly superior to PPIII.
Just my $0.02.
GZ