And don't forget, those tanks are made out of fiberglass. Eventually if you leave dirty bluejuice in them, the smell will get impregnated into the tank and you will not even be able to bleach it out....
We had to replace our holding tanks on our G4sp many moons ago because of this.
We have vacuum lavs on our G450 G650 and Global and we still dump the lav after every trip (ever been outside when a vacuum lav is flushed on the ground and its full
). Its cheap insurance to not have the plane smell like a farm!