I placed a deposit at HomeDec for DC-Heater yesterday.  Based on what the sales person mentioned and demonstrated, I'm quite convinced. Main features - low power consumption 350-750watts vs conventional 3000watts, no heating elements hence no risk of electrical shock. A fiend of mine bought the same brand at last year's HomeDec and have no complaints to-date.

Sales person mentioned that it only takes less than 5 min to heat up IF the switch has been switched off earlier.  Unlike conventional ways, she advised to keep the switch on 24/7 (cos it's low power consumption) unless you intend to go for holidays. She had a demo on the plate which is used in their water heaters. With just a little voltage from the cell battery, the plate took merely few seconds to heat up.

I am getting the tank heater.  If not mistaken, the instant water heater is RM799 with pump