Membrane wont easily get clog? 

Mainly because water in Malaysia is very soft. In USA, where water is very hard, if you do not use RO, all your appliances such as kettle, coffee machine, humidifier etc, will be covered in white deposits. So it is a huge advantage for them to get RO, though it wastes 4:1 water in some cases and water is precious there (think California for example). Here in Malaysia, main advantage of RO is missing since no calcium deposits anyway, so RO must be extremely efficient here to compete with non RO systems. Though of course quality RO system will offer the most pure drinking water.

Another reason is this strong propaganda "RO water is bad for you", which is complete BS, but hey, when everyone says it, people start believing.

By the way, now possible to pay for our products or any other products for that matter by installments through Shopee or Lazada, so main advantage of Coway is slowly disappearing

There was a fellow member not so long ago for whom money did not matter much, so he was only considering the most expensive systems, he asked me for advice, presenting few systems on his shortlist. Between Coway, Cuckoo Panasonic and eSpring, choose eSpring if money is not an issue.