If he doesn't like the recoil from a gas operated gun like the 1100 - he only has one option on that gun - and its to add some weight to the gun. If he can add 1 lb to the gun / it will reduce the recoil almost 12%.
The trick is to add it without fouling up the balance of the gun / so some under the foreend / some in the butt ( using lead tape, etc ).
All of the gas operated guns ( Remington, Browning, Beretta, etc are all going to give you about the same amount of recoil ) - and they're soft shooting guns, if they fit you / if they don't fit - they will beat you up. But like OneOunce said --- Fit, is the key.
The inertia operated guns - are a plus in my opinion / Benelli, etc - but if they are not a synthetic stock, with the Benelli Comfort Tech system built into the stock - they will probably give you 20% more recoil than a gas operated gun. If they have the Comfort Tech system - I think the recoil is about the same as a gas gun ....
$1,000 - $1,750 for a versatile shotgun is not expensive in my opinion / but you didn't say what your buddies budget is .... Remington, Benelli, etc both offer some left handed models .....
In terms of gas operated guns - I think the Rem 1100 and the Beretta 390/391 series are very good guns. On the Inertia guns - I like Benelli.