Alex, no offense but its nothing at all to do with it being "an easier product to sell" LOL you make it sound like thats all ionics are bothered about lol (which is what I think you were trying to do, thereby having a sly dig at ionics. My advice: when you dont know what your talking about its best not to try to sound clever)
I looked at all of the options when it came to getting my setup, and water filters on the system in the van was the best solution for me.
However, ionics did advise me that if I were planning to get more vans on the road, it would be more economical to have a static set up with just what they were calling a "delivery system" in the van. IE, Only the water heater, and a single DI filter just to polish, no other purification.
The idea being that you have your static system at your premises which is constantly making pure water and stored in big tanks. Then, when you drive your vans in you use a transfer pump to get some of the ready made pure water into the tank in your van. Takes a couple a minutes to transfer.
So your van only has the tank, the heater and maybe just one or two DI filters just to make sure the water is always pure to the pole.
As I wasnt planning on getting any pmore vans on the road/employees just yet, this was not right for me, and it had nothing at all to do with being "an easier product to sell". LOL what a ridiculous thing to say.