I know that the first rounds of UCD and NUIG acceptances are alredy out, so if you have not got anything yet, then I do not believe that you'll get anything from UCD or NUIG before the RCSI deadline. May be you want to double check with Atlantic Bridge.
I was in the same situation and I already sent my deposit to RCSI for a very simple reason. RCSI provides the resources to support you during your last year to pass the board exams in Canada and the USA. RCSI also accommodates the residency interview schedules in Canada and the USA, while UCD and NUIG do not do that. I figured that would save me a year or at least I'll go to the residency interviews not worrying about my final exams. Good luck.