I did DUB-JFK twice last year and DUB-ATL once -- all three times we cleared customs in DUB as well -- were let off at a "domestic" gate every time. If you have checked luggage they show you a picture of it on a monitor and ask you to verify it is your luggage. Just like when I precleared in YVR.

And there are now some amenities post pre-clearance -- no lounge but snack bars and stuff.