3.5" shells were intended for the military and law enforcement so they could shoot "less than lethal" exotic loads, ie bigger bean bags teargas or just good old flachetts, to take out people wareing body armor. they are also marketed to duck and goose hunters that would have normaly used a 10ga now you only have to buy 1 gun to do many tasks. i personaly feel that its a lot of hype and a 2.75 is just fine for what i do, upland game and clays, heck i usualy shoot the lightest thing i can so i can shoot more cheeper