Most of my Irish-speaking friends are from Ulster (the nine counties), and they say that the Irish taught in schools is nothing like what is actually spoken. Guest 999's transcription of Clannad's singing is close to what I would expect from my knowledge of Gaelic, and I find that Donegal Irish shares a lot of it's pronunciation with Gaelic, eg dubh pronounced doo rather than duv. Similarly, Argyll Gaelic has frequently been berated for its 'Irishisms'.