Gas Piston vs DI for semi-auto rifles

[PhotonGuy]

Semi automatic rifles on the M16 platform function either by DI (Direct Impingement) where gas is channeled by a tube from the barrel directly to the bolt carrier mechanism. The pressure from the gas is used to eject the spent case and feed a new live round into the chamber to be fired. With gas piston the gas is not directed to the chamber but rather it pushes a piston which pushes the bolt carrier and ejects the spent cartridge while loading a new round. Which system does everybody prefer? Some people say with the gas piston mechanism you're adding an unnecessary step and that it unbalances the weapon. Other people say with the DI it fouls up the chamber and is more prone for malfunction. As it is, a gas piston weapon is about three times the price of a DI weapon. Some people though prefer the DI system even if price wasn't an issue. So which system do people here prefer?