I fly between ICN and US fairly often. Sometimes I'm able to route US-DFW-HKG-ICN for the same price as just flying US-DFW-ICN. I do this to get on AA 777-300 which is better in any class than the 777-200. That being said, I probably wouldn't do this if I was trying to upgrade four people using miles. This is the most difficult upgrade in the system. I would stay on how you are currently ticketed even thought the biz seats aren't as nice. It seems to be a fairly easy upgrade, and is MUCH better than Y class.