You obviously have not shopped at a Gristides. They are not in the outter boroughs of the city (as far as I am aware), thus their function as a distribution outlet is limited, but their stores sit right in the midst of a more affluent audience. That's who they cater to and the items in the store typically reflect that. Not all items for certain, byt please do not lump them in the category of a Walmarts or Pathmark. You are far off the mark there.
The difference between them and Whole Foods is that they are more like a 'Mom and Pop shop', They do have several stores, but it's a local thing...and def high end if you're using Whole Foods as a comparison.
As how does this benefit MINE? Time will tell. If you ask me, they get to say they are on Gristides' shelves as they look to 'hawk their wares' to other vendors in the NYC metro area. That is not a bad client to have in your portfolio if your expanding into a busy market like NYC.