Just another side note MichaelJ.

Don't let the recoil of a 12 ga put you off. Try one out if you are not familiar to see how you handle it. Some people have problems and some don't but as others have said, it's hard for any 20 ga to come close to the performance of a 12 ga. Most 12s take a whole gambit of different ammo ranging from reduced recoil 2 3/4 inch to 3 1/2 inch magnums. If recoil is a concern then you have the ability with a 12 ga to drop to less powerful ammo. If you have a 20 and find you need MORE power, your options are limited. Barrel porting etc can also be considered as an option to drop felt recoil(most new models come ported from the factory)

a 12 ga with a ported barrel, a good shoulder pad, a heavy stock and reduced recoil rounds will have very light felt recoil. You will have the added pellet count and the versatility of still being able to go up in power if needed.