Originally Posted by
mosburger
Apart of not having alliance-wide extra baggage allowance for tier card holder (and AFAIK this is mostly due to BA reluctance) OW also does not feature alliance-wide MFU opportunities as opposed to Star. As we all know only Asia Miles can be used to upgrade other OW carriers (AA and BA) flights from certain booking classes.
That's likely to change, at least for IB, AA, and BA given the antitrust exemption.