I guess I'm not partial to either system, but my autoloader experience is rather limited and it's with the old-school stuff too...
Browning Auto-5, Remington 11 & 11-48 for inertia guns and the Remington 1100/11-87 and Mossberg 935 for gassers.
I don't own any of em, but my favorite of the ones listed above is a 26"bbl 935 that a friend owns. It just fits me like a glove, even better than my 870s, and I can shoot mourning doves and pheasant with it all day long.
We've had to replace the o-rings in the gas system a couple times over 10years or so.
1100s are about the same...you need to maintain the gas system. Most gas-operated guns will feed whatever ammo you shove up the tube with no adjustments though.
With the older inertia actions like the Auto-5, you need to set the action for the weight of load you're shooting to ensure solid functioning. Can't say for sure about the newer inertias like the Bennelli.
The Auto-5 design has been around since 1900 or so (yeat another JMB classic!) and is a proven performer. But the 1100 is a very reliable design too...
Waffle...waffle...notcommitingmyselftoeithersystem. 
For some reason, I've always preferred pumps over autos when it comes to shotguns.