I may have missed this in the national press or maybe this is simply not true, but the
Wicklow Times had a front page article a few weeks ago that the pass rate at the privately run driving test centers is 63% while the pass rate at the state run centers is 54%. So you have a better chance of passing if you go private. The article provides all sorts of (not unreasonable) explanations for the difference in the pass rates, but still I think if I had to take my test I'd look for a private test center.