Anybody has experience with instant electric water heaters? For those who do not know it, it is a very small water heater without any tank and consumes a huge amount of electricity but only when you open the hot water tap & stops immediately when you close the tap. The hot water never runs out & it is heated in a second. I know they were in the range of 2-3,000 LE. But anybody has experience with them? Advantages & disadvantages, the good brands, approximate price, any after sale service required? Thanks!