I was on the six across 772 from HKG to SIN a month and a half ago. The flight was 9AM to 1PM, so there was no opportunity to deploy the lie flat seat. It was a comfortable enough seat and I ended up falling asleep for an hour after the meal.

it is what it is, business class on a regional, relatively short route (and, yes, after the long haul from SFO to HKG, four hours seems like a puddle jump.)