There are advantages to a flow controller. In the end it comes down to what works best for you.
I would be interested to know what controller you are using? how old it is? and what happened to it? Did it just die?
The controller may be repairable at a lower cost than a possible replacement
1. In running the pump until it hits the pressure switch you are running the pump as hard as it can possibly work. This means that the pressure in the system will be at its absolute maximum. This puts strain on the hoses, on the fittings and on the pump. It therefore increases the chances of split hoses, leaking joints and increases wear on your pump, shortening its life.
2. As the pressure switch cuts out the pump is at maximum, working as hard as it possible can and therefore drawing maximum current from the battery. Hence as the switch opens it too is under great strain. The high current and the fact that the pump is an inductive load (with stored energy) means that the pressure switch contacts are likely to arc and eventually they will fail.
3. Without a controller the pump will not stop until it hits the pressure switch. With a controller with dead end detection properly calibrated the pump will be stopped a long time before this high pressure and high pump load. This means that because the pump is turned off earlier you are saving battery energy and hence increasing both the battery life but also the amount of time you can work on a battery charge.
Cheers
Ian