The RnaG podcast linked below is an interview with a sean-nós singer from Cúil Aodha. As well as all the usual places that a Munster speaker would make a 'v' sound instead of a 'w' sound, she even pronounces 'amhrán' with a 'v' sound! The interviewer sounds like a Kerryman and at one point (2m30s in) he even pronounces the word his way before re-pronouncing it her way, as though to stress that he's referring to the sean-nós of Múscraí.

Would it be fair to say then that Múscraí represents one extremity of the w-to-v spectrum or is there another community in Munster who take it even further?

http://www.rte.ie/podcasts/2009/pc/pod-v-160909-08m47s-ansaolodheasfodhla.mp3

I had a teacher from Cúil Aodha, he'd pronounce amhrán like "avarán" /avə'rɑ:n/.

He'd say "an bhfuil" like /ə'vwɪl'/. Almost all bh's and mh's like v's, even broad ones.

I think you misunderstand the issue. There is no "w/v" spectrum in Munster at all. Everytime "mh/bh" is pronounced as consonant, it is pronounced as [v], pronunciation as [w] simply does not exist. Yet, usually when those consonants follow a vowel, the sound is merged to produce diphthong [au] like in English word "house", e.g. amhras [aur@s]. The words "amhrán" and "amharc" are extraordinarily pronounced [av@ra:n] and [av@rk] in Cork, as opposed to Kerry's [aura:n] and [aurk]