I purchased a Mossberg model 500 at Wal-Mart for $257, which had a factory ported 28" barrel. In comparison to my 28" 870 and 28" BPS, both of which are heavier than the 28" 500, I believe that I detect less muzzle rise after the shot when using the 500.
I've gotten some impressive patterns through the Model 500, with #7.5 Lead loads through the factory Improved Cylinder, and the factory Full chokes at 30 yards. A .675 Undertaker Non-Ported choke shot really tight patterns with #7.5 Lead from 20-25-30 yards. A .690 Primo's Dead Deer choke did very well with 00 Buck at 35 yards.