I'd do it.
If that makes any difference to you, I'd do it.
Discuss the possibility with your graduate school adviser, and even if you risk losing out on one year of graduate school, you will regret not earning Summa cum Laude for the rest of year life.
At least I would consider starting graduate school a year later if it meant earning that level of distinction.
You should give it serious thought. Of course, on the flip side, if you're already admitted to graduate school, then Summa distinction probably won't matter too much when you're "job hunting" but it'd still be something you should be proud of, and telling colleagues/possible employers you were almost Summa just won't cut it.