Heck it ever hurts to own all the gauges you can.....
I have a MAD 10 ga turkey gun, 12 ga tracker II, 12 ga ultra, 12 ga 28 polly choke, 16 ga 28 in full choke, 20 ga 26 in mod choke, 20 ga tracker II, 28 ga 26 in mod and a 410 26 in full choke.
Congrats on the 20 you will love it.
But I guess I'm the kinda of guy that thinks bigger is better...I like my 12's for the payload they can shoot, But I have times when the smaller gauge guns are just down right fun to shoot.