I've read through older posts here that strongly advise starting a car rental from the airport rather than downtown. Is it really that bad? On the morning we leave Dublin, we'll still have active LEAP cards, so would take the AirLink bus - but it takes an hour to get from Heuston Station to the airport and it's exactly opposite to the way I want to go. We're headed to County Kerry but I wanted to meander down the coast, go to Glendalough and Wexford, then over to Cordal, rather than taking the motorway straight through the middle of the country. We have all day, not in any rush.
If it helps, I drove a stick shift at home for more than 20 years, I have driven a stick shift in England successfully years ago, and will have just driven in England again on their narrow roads surrounded by hedgerows. I'm a good, accident-free but not overconfident driver and will have both an electronic (Google Maps) and a human navigator with me.
Do you really think I need to go to the airport first to avoid the hassle of getting out of downtown? The car rental office is on South Lotts Rd near Aviva Stadium.