Not to disagree with the well knowledged people on here, but I agree with Chuck H. (Not that he isn't well knowledged also)

But I would keep the Super. When you say "collection" I am assuming that you can probably afford the BSS. Add one to you collection in a 20. They are sweet guns, too. But I really love my 20 gauge Super. It is such a nice little gun, too. I took Pete Hiatt's advice when I bought it and I wouldn't part with it. I also have a Miroku SXS and it is nice, too. So, you have other options. If you are attached to the Super, go out and look at the BSS before you sell it. All are nice guns, so take your time before deciding. Good luck with your decision.