I finally pulled the trigger on this. Here are my initial data points using login information on portal pages. iPass app did not autoconnect on any of these.
Gogo on AA: Fail "Activation Error"
AA Inflight (Panasonic solution on international planes) : Success using ipass login link on splash page
Cathay Pacific (Panasonic on A350): Fail Nowhere to use roaming for iPass accounts that I could find.