Its not just imagine: Clonmel-Dublin via Limerick Junction wins hands down.
1. Clommel - Waterford and Clonmel Lim Jcn are more or less the same time and distance.
2. Lim Jcn to Dublin is more or less every hour: Waterford-Dublin more or less every 2 hours, so the connection opportunities with the former are much better.
3. Lim Jcn- Dublin is 90 to 110 minutes at present: Waterford-Dublin is 120 to 150 mminutes for the most part.