I have been in J on award tickets, paid tickets, paid upgrades and op ups; had different experiences but can't link them to the type of ticket. While of course the number of passengers in the cabin is a big factor, I believe the service level is mostly dependant on the crew or even the particular crew member that is assigned to your aisle. I have had wonderful experiences where you don't feel you have to ask anything, all is just there or suggested at the right time and I have experienced crews that were mostly keen on making themselves as invisible as possible.
I switch between CX and EY for my Europe to Asia flights, the biggest reason I prefer CX in J is because of service level consistency.