We do dairies, cattle feed lots, hog and chicken farms, fish farms, all kinds of irrigation and potable water systems using CSV's. I have an irrigation system in Florida with 11 water wells scattered many miles apart. These use a CSV and small tank at each well, with the pressure staggered and using 3 PSI between on and off for each pump. There are no wires running between the wells as would be needed with VFD's. There is only 33 PSI difference between only one well running and all 11 running at the same time. And this could be tightened up a lot more if we let a few pumps come on at the same pressure.
One of our oldest systems is a 40,000 head feed yard in Liberal Kansas. They started using CSV's back in 94 to keep from having to replace motors, especially a 100HP turbine motor every 6 months. They even had a spare 100HP motor sitting in the well house ready for the next change out, as the motor was destroyed regularly by all the cycling. I believe that spare motor is still sitting unused in the well house, as they have not burned up a motor since installing CSV's. They have 6 or 7 well tied together by staggering the pressures as we do.
We also replace a lot of VFD's on dairies. The stray voltage from these VFD's cause the cows to reduce milk production, mastitis of the udder, still born calves, and even erases the data on the cows electronic ear tags. All of these problems go away once the CSV's have replaced the VFD's, and milk production has been know to increase by 50% within days.
With the way CSV's control pumps, I would only use a reservoir if the wells could not keep up with peak demands. But if a reservoir is needed, the CSV's can control the well pumps without any wires running from the wells to the reservoir. The pressure switch/pressure tank turns each pump on and off as needed, and the level control in the reservoir simply opens and closes an electric valve at the bottom of the reservoir as needed. I have even done this with float valves when there is no power at the reservoir.
Then CSV's can also control the 4 or so pumps that pump out of the reservoir. You would just need an 80 gallon size pressure tank with 4 pressure switches on it to control 4 pumps with CSV's.