SQ, fully flat? I take it you have never been on their A330's or their regional 777's then? In fact think they may still have some aircraft that have sit-up J seats. If not only gone in last year or so. SIN-CGK used to be a lottery for business class seats. Sit-ups, angled flat, old long haul flat, new long haul flat. But hey grass is greener isn't it when your just bagging Qantas for the sake of it.
As for CX and the long haul fleet and speed of install, simple maths really. More aircraft in fleet=more can be taken out of service to be done concurrently without it effecting day to day operations.