One of the most important reasons why many are turning to tank-less heaters is because of how cost efficient they are. Tank-less units only heat up the water you are using. They don't heat up and then store unused water. Tank-less water heaters are amazing and becoming more and more popular. Those who have them will never go back to a typical storage water heater for many reasons.
Also, they cut the bill by not storing water. Because it is only working when it is used it saves energy up to 50%. This will generally cut off about 10 to 20 percent off of your water heater bill. And with the economy how it is right now, who doesn't want to save on their utility bill. These tank-less units supply instant heat at the temperature that you've assigned. Among having endless amounts of water, they also have less maintenance work that typically needs to be done on regular tank water heaters.