3 Jan. 08
I own 2 Winchester X2s and an I-12. The current I-12 seems quite reliable and if it is totally immersed in water, it would be easier to strip, dry and clean. However unless the gun goes for a swim, the X2/X3 is also easy to clean. The advantage of the I-12 is that there is no spring loaded piston in the butt to push the bolt into battery. If it gets wet, there is no need to try and remove that piston, drain and lube it. I believe the Benelli guns have the piston and wouldn't have that particular advantage.
One other factor is recoil. Say what you will, ID guns kick more then gas operated guns. There is a distinct difference in the recoil of my X2 Composite and my Franchi I-12 when shooting the same heavy duck loads.
If recoil doesn't bother you, then it matters not. If it does and you'd like to get back on target a little quicker, you might think about the gas guns.
DumbDuck