Booster pump help to get the proper pressure through your rodi thus making the system more efficient. It depends how much pressure your water is coming into house
A booster pump increases the pressure on the input side of the membrane. A permeate pump lowers the pressure on the back of the membrane by pumping the water that went through the membrane out. Both act to increase the pressure difference across the membrane but in opposite ways.
If you have good input pressure then a permeate pump is the way to go to increase the system efficiency.
I have one on my kitchen sink. Someone before described the physics of these pumps, and yes it does improve water production efficiency. The one I have is noisy, we can hear it when the unit is making water and the exhaust water is expelled down the drain.