I have been looking online at a new Beretta shotgun for me and my son. I have a Beretta Xtreme Unico now and we both love it. Can someone give some insight on the differences, if any, between the Beretta Xtreme Unico and the Beretta Xtreme Plus (other than the cheek cushion and the bolt handle and bolt release and any of the other outside physical changes...basically, is it the same gun on the internal components???? Lastly, is the A400 Lite the same gun as the above, just in a 3" rather than 3 1/2??