/m/ in every other Sinitic languages (including every other Min ones) correspond to /b/ in Southern Min (Hokkien etc.) in many, if not most, of the cases:
(Note: Mandarin / Cantonese / Hokkien)
米 : mi3 / məi5 / bi2
木 : mu4 / muk6 / bok8
馬 : ma3 / ma5 / be2
Preceeding a nasal final, however, /m/ seems to be retained:
麵 = mien4 / min6 / mi7
However...
閩 = min3 / mən5 / bin5
明 = ming2 / ming4 / beng5
Any rule governing such /m/ > /b/ shift?