The contradiction in McGee's site (and the many others like it) is that they are advocating as a folk instrument a very specific type of REALLY REALLY EXPENSIVE flute which virtually none of the creators of the Irish folk repertoire could possibly have afforded.

My greatgrandfather (from the West of Ireland) joined the British Army as a boy, went to fight in Afghanistan and came back having learned to play the flute.   Victoria's Army didn't supply Prattens and the like, they got shiploads of el-cheapo no-name German flutes which may have had iffy out-of-the-box intonation but which stayed in circulation for decades. I've got one of them; intonation not too bad, not the easiest thing to sound, not much use above third-octave G and its market value is that of an *adequate* instrument, i.e. probably no more than the OP is thinking of paying (rather than add-a-zero-and-then-some for a Pratten or McGee). But my ggf might have recognized it, and so might Captain O'Neill.

The question is whether you want to play folk music or some concert-stage simulacrum of it.