Doubtful, unless you have a need to be in that terminal for another flight. I've seen that store and I was unimpressed. Why spend more at an airport? Just go to a mall in the Boston area to get what yu want or just order online.
"If you can't delight in the misery of others then you don't deserve to be a college football fan."
No, you won't be able to access the Bose store. DL's terminal is situated by itself, so only DL passengers can get to the Bose store, and either way, it's a haul from Terminal E, as you have to cut across the airport, and then the Bose store is located in Terminal A's satellite.