There are some set-ups that will benefit from some form of electronic control and some people who feel that they benefit from them, no two people or systems are ever the same. Commercial Van-Mount systems tend to be built with them as standard as they can 'idiot proof' a new system for a the user (hence less customer support needed). Our Van-Mount systems are built with them on for just this reason.
To have a truly adjustable flow rate you would need to use 1/2" hose instead of microbore, then you could in effect increase the flow rate. You will never, even with a 'flow controller', be able to increase the flow past your maximum system rating.
The one advantage of a flow controller is longer battery life, as it controls the speed at which the pump spins, hence prolonging the life of the battery. If battery life is not a critical factor in your set-up, then all it will really do is give you the ability to reduce your flow rate down. Personally I know what I like my flow rate to be and I stick to it. I can occasionally reduce it for short periods of time with my pole control valve. Does this put more strain on the pump? Yes, but they seem to be able to cope with it, after all, it is only the equivalent of putting a longer length of hose on the pump.
My first pump (60psi) lasted for 5 years of full time use, the second pump (60psi) I added to my system to make a twin pump system lasted for 3 1/2 years. Both pumps were then made redundant about 1 1/2 years ago as I now use just 1x 100psi pump to power both poles on 100 meters of microbore. The 2 original pumps are still fully working and are kept in the vehicle as spares. The current pump has given good service for 1 1/2 years. All of the pumps have been run on my 'electronic controller' free set-up. My trailer system has 1x 100psi pump which has been used this way as well for 4 years.
One of our workforce has worn a pump out after 3 1/2 years. It was a 60psi and was used to power 2 poles for that time for 5 days a week 6-7 hours a day. In the end the seals and diaphragm went - we thought it deserved a rest!
I have just fitted my system with a new type of electronic control purely to test it out for the manufacturer. I will be able to tell when I next work how well it performs, but at the moment my system does not technically need such a device. With 2x 100 meters of microbore to power I think that I will just end up leaving the dial set to maximum, effectively eliminating the device!