Thanks William - just to clarify, the rationale I don't have is why a-moz.groupbuyseo.org mentions that the "notable exception to preferring subfolders is language specific sites".

My inclination is to go with subfolders (as we would if we were e.g. launching a blog), but since the standard advice has a caveat for language specific sites, I'd like to understand why this is so before making a decision.