There's plenty of non-league sides capable of holding their own in the First Division. In one-off games they've shown they're capable of showing up plenty of LOI teams in cup games, Crumlin and Avondale two mentioned to have beaten or drawn with Harps being good examples yeah.
There's no point at all in worrying about how promoted clubs would do against Dundalk, and that's exactly the point I was trying to make.
Worrying about how clubs would do on the field with their current squads is nonsense. Looking at extending the league wherever possible should be high up on the list of priorities for the FAI but that requires too much effort.