I have a tap TDS of around 65, I have recently changed to an van mount 40/40 RO system, wish I had done it sooner, TDS from RO is 000, I still go through a DI to give the water an extra polish, the system will have paid for itself in the first year, I will then have pure water made very cheaply.
I installed an Auto-Flush control from Jet Systems, saves on all the weekly flushing.
Go for it, potential savings are huge.