Keep both and use them if finances allow. I have a 26" 20 Trojan, got my Doubles Pin with it at 40 yards on doves. Such a sweet handler that the pretty daughter has claimed it.

Thanks
 

I really appreciate everyone's opinions. I think I'll keep them both for a while and shoot them. Because of Charlie's answer I am leaning toward the 20 as I have other 12's to shoot. Also if the house were on fire I would probably take the 20 as it would not slow me down as much.

I like the idea of enjoying both, you may be surprised which one you shoot best and if the price is right, enjoy. I'm not an experienced shooter but what you read says the follow through with the short barrels is more difficult but being out on a good fall day and carrying a Parker is a great day! Fall is not far away now.