De facto,
Many of your claims are more typical of a Microsoft flightsimulator teenage boy than of an experienced airline pilot
"Closer to the overspeed conditions" are you kidding me?! 320kts. is a good standard of descend speed on NG in stable air.
"uncomfortable for the passengers" My god man, you don't know what you are talking about! It has nil, zippo nada efect on pax. comfort if you transition from level to idle descend when doing it correctly and don't slam the thrust levers etc... it is called airmanship. (but wait, I see your profile does say location China...)
In my company, we do NOT have a fuel policy, we use CI35, but this is to the discretion of the commander...