In the last few days I've been browsing through the map, with the SI 188 of 2006 in one window, and the NLS Historic Maps in the background of JOSM. I've corrected a bunch of road refs, and managed to add or complete a few other roads that were completely missing through Counties Cork, Kerry, Limerick, Clare, Tipperary, Waterford, Donegal, Cavan and Monaghan.
I think the list on the Wiki needs two separate completion columns, one to say "an armchair mapper can see that everything listed in the SI seems to be there" and "somebody on the ground has confirmed this is actually correct".
Oh, and where exactly does the R162 really go when it heads north of Shercock? No sign of Lisdrumclave on the historic maps. Ta. :)
I'm also not convinced that R268 in Donegal is right. Doesn't seem to match the description.