The impact pump will use more water vs. the Hi pressure pump unless you have a water recycle system. If you do have a water recycle system the Hi impact pump will work better with recycle water. The rotary pump of the Hi impact is more forgiving with recycled water. I had a company that sells spray nozzles run me a impingement graph to compare the two systems before I bought them. Impingement is based on the impact of the water on a vehicle surface. Even though the Hi impact runs at a lower pressure it is using more water ( in essence it is using a bigger bullet) and in order for the Hi pressure unit to have the same impingement as the Hi impact it would have to run at 1400 psi.
I am sure the water cost between the systems would be less than a nickel per wash or less. Actual run time of the large pump per wash is around 45 seconds so the Hi impact you might use 15 to 20 gallons more per wash but could be closer depending on the run speed you set up. I am sure Ryko would have the water usage difference. With the Hi pressure unit you would have to replace costly pulsation dampeners and belts that the Hi impact does not need. Plus the rotary pump will run forever. I have never had to address one large Rotary pump ever.
I can change most swivels myself. The only one I do not attempt is the one that sits over the arm rotate gear box. TO change it you have to take off the arm and gear box and locating proxes. I am sure I could do it but my tech is much better at it and I would rather pay him to do it.
I have only had a couple of cable issues in the booms. If the wires are put in right at first with enough slack on the wall you should never have problem. I have had a couple of broken wires in the boom but it is usually a pretty easy fix. Control wires are the only ones I ever had trouble with.
As for Steve"s problem with customers thinking that only the right side gets the low pressure functions sometimes I addressed it as follows. I had a large pictograph sign made years ago that explains that presoak and Hi pressure comes out of the arm. All other function use overhead manifolds for trifoam wax, rinses, clear coat etc. The pictogram shows the halo arch spraying these low pressure functions. I mount the sign in the bay right outside the drivers window where they are parked during the wash. I almost never have anyone complain about the "right side only" application now. PS I gave RYKO copies of my signs years ago and told them they needed to send a similar sign out with every unit they sold. I don't think they ever did but I would still encourage them to do so.