I had had SIN-NRT-ORD-BOS with 7-hour connection at ORD. I had planned to request SDC at NRT United Club (UC) for an earlier ORD-BOS flight which had a few Y seats open. Upon landing at NRT, I was called by the flight attendant to receive a message at United Club. Fortunately it was not bad news. NRT-ORD (operated by a 744) was oversold by 15. The agent at UC asked if I could take NRT-EWR-BOS instead to arrive BOS about 4 hours earlier. I asked about VDB compensation. He said that there was no compensation because I would arrive BOS earlier. I took the offer because I could have power outlet for my laptop to work with on the NRT-EWR flight operated by 772. He booked me into booking class Y for NRT-EWR-BOS upon my request. At the gate, I was op-uped to C because Y was oversold. A solid 7-hour sleep was really good to eliminate jet lag. And the extra PQMs look good to me.