I have the Pure Freedom boosted system it’s fantastic tbh a bag of resin will give me 3 changes so I won’t use anymore than 2 bags a year max I reckon,even at low TDS it’s worth an RO why would you resin only with low TDS if you had a decent RO you could get the water down to around 2-5PPM and work with that,that would be cheaper than DI only.