I don't have experience of this in Ireland, but I briefly tried it in the UK a couple of years ago and it was anything but a good experience.
The same system of "top-up" aplied there, but the chances of collecting the extra money from the tenants was nil in most cases. They tended to be antisocial drongos generally, and they couldn't understand that they themselves should have to make any kind of contribution to society. If however you tried to move them on for non-payment of rent due to the lack of "top-up", you were up against the might of the social services and their teams of social workers, drug counsellors, and asociated parisites.
Best advice in this area would be to let the county council build their own houses and for landlords to keep away from this sector. It does make a living for some dedicated landlords who don't mind the grief, but it's not for the faint hearted. And yes, council tenants (in my experience) don't look after properties -- they have been conditioned to expect that everything will be done for them and won't lift a finger to maintain or protect the landlord's investment. I know, that's a sweeping generalisation and unfair to the good tenants, but its my experience of the sector.