I'd disagree a bit Ryan. Some of the better teams, Sligo, Shamrock etc would easily slot into League One.
Ninja, the attendances are a bit hit & miss. Derry would see a couple of thousand tops, Sligo and again Rovers would top that and so in turn would probably reflect in their budgets and position in the league. On the other hand, a team like UCD (University College Dublin), who have a ground,players, and good training facilities (courtesy of the university) and a smattering of people of home games but that's always been the way. For example, the actor who played Father Ted, can't remember his name right now, Dermot something or other, was asked why he supported UCD, his answer was "I like the solitude" or something similiar.
The league have tried to counteract the attendance issue. The games have been played on Fridays for quite a few years now to balance out the people heading over to support, or who just sit on their arse in a bar going to see English (or Celtic) teams (and I'm guilty with Liverpool). They've also changed it to a more a less summer league which has also helped.