I'm assuming the store exclusive you're referring to is the grey Sunday swagger? Definitely look for a used one on here, way cheaper. They're tanks too, so don't sweat about it being used. The grey ones will have new utrip stamp and 2004 Asa stamp, the white ones are mixed, some have new utrip stamp, some have old. All have the old 2004 Asa stamp. The Easton L6.0 is Asa only and has new stamp. Make sure you you are buying the right bat for your league and meets their stamp requirements.
As for performance, both are excellent bats. I own both and like them equally. The Easton is going to be the better of the two out of the wrapper with a much shorter break in. Was hot right away, but really took off after 150 hits or so. Softer barrel then the demarini and has slight end load
The Sunday swagger is an absolute log out of the wrapper and sounds almost like an aluminum bat. After about 300 hits the sound started changing to a louder crack and there was a noticeable difference in distance and exit speed. Now I've got around 800 swings and it is an absolute fire stick. It's almost up there with cl22. The end load is more noticeable to me in my 26oz Sunday swagger than my 27oz L6.
After break in, I'd probably say the Sunday Swagger out performs the L6, in my opinion. By the way, these reviews are with a mix of ASA gold dots and various utrip balls. If you only play ASA and your league uses the 52's or Hot Dots, I personally would get the Easton. It performs better with the 52's. If you play utrip/tournaments or think you might and don't want multiple bats, I'd go with the swagger.
Anyways, I hope it actually was a Sunday Swagger you were looking at... If not, you're welcome for the Easton L6 review and the Sunday Swagger recommendation. Haha