As far as I am aware, peak hour constraints used apply to Dublin Bus only. In any event, the only serious case for its introduction are for the morning peak on DB, and IE on Dublin Suburban and DART. Provincial services are not as subject to serious and persistent overcrowding.
A question for Mark G. Could you elaborate more on the Companion issue. Is the availability too generous and are there specific abuses which even the politically timid might consider doing something about?