Another unfortunate downside here, though -- including a leg with another airline's ticke number (rather than an AA codeshare) makes the entire fare ineligible for 10% off via S617HG. For my routing, an additional $20 of taxes result, making BOS-JFK-NRT-HKG-SIN-NRT-JFK-BOS about $80 more expensive, all told, than BOS-JFK-NRT-SIN-NRT-JFK-BOS. Hmm.