Personally I'd rather do an I=>D at SFO than an I=>I at TPE, but I have GE and Pre, and I find the TPE transit extremely unpleasant, especially during the early morning crunch. To me the negative of the SEA-SFO-HKG itinerary is the potentially risky SFO transit on the outbound. I nearly missed on one of these just last month due to a delayed UA crew.