Recently travelled to Atlanta with Delta. On the way out we did have to stopover in Shannon, you do have to disembark and bring all your hand luggage with you. Word of warning, phone Delta and confirm flights a few days before you travel. I booked and paid for flights via Delta website in December, arrived at Dublin airport in February and was told "that flight was cancelled weeks ago". They re-booked me for the next day. Same thing happened on way home - ended up flying via Paris! Have applied for that EU compensation from them but no word yet!