First Let find out what is the Difference Between Timer and meter
The main difference between these water softeners is that a meter controlled unit measures the amount of water being used in the household when the water usage hits a preset level then the unit regenerates (goes through cleaning cycle), while a timer controlled unit simply regenerates at a preset time each day regardless of the amount of water used. If your water usage changes from week to week then the metered controlled would be more efficient for you. If your water usage remains the same week to week then the timer controlled would be ok to use. Unit size then depends on the number of people in the household.
In your house if you have a water meter and you get charged for the water you use the meter water softener would be a better unit for you as when it does a regeneration it would only use 35 liters of water with a timer water softener it would use 160 liters per regeneration the meter water softener would be more efficient less water been use on regeneration and less salt been used.
What is the flow rate [water pressure] coming from the water softener all our water softener has a flow rate of 118 litres per minute so you would not have any pressure loss with the water softener