Just expanding on the issue about codeshares, here is a good example of where OW programmes work better than *A.

Take for example an AA programme member wanting to travel on BA J from LHR to SYD but wants to get the elite bonus QF offers. The AA member would book the QF coded BA flight which would entitle the AA programme member to the elite bonus yet travel on BA.

Another example would be a QF member wanting to get the elite bonus offered on BA flights on a service between LHR and HEL which is not offered on AY. The member prefers to travel AY over BA so can take a BA coded AY flight to get the elite bonus offered on BA flights.

The above examples would be not possible on *A as on *A programmes, it is the metal which counts and not the code, not to mention the issue surrounding how fare class codes translate between carriers (*A carriers are not so good on the fare class harmonisation side). To expand on this, a BD member wanting to take a BD coded flight operated by SQ metal for example in J class between LHR and SIN would find they would still only get the SQ J class COS of 1.5 x compared to the 2.0 x offered by BD itself.

Just some food for thought.