u really need to check your water pressure, bear in mind each area, and even estates, differ. then you can make an informed decision for which RO to go for. I ratherered spend more and do a better, quicker, job.
also your tap tds.
I had my 4040 RO in van to start off, parked it on drive for 3 hours a night, hose through the house via booster pump. don't really want booster pump exposed for security. I also had 2 holes drilled in van floor for inlet water to RO and waste from, this way van could be locked.