Room Savings vs. Cost
The tankless water heaters were actually intended as space savers. So, the biggest advantage of installing a tankless water heater is that you are going to save a significant amount of space. So, if this is your concern then you should go ahead and install one. But, realize that the cost of a tankless water heater and installation are going to be significantly more than a traditional water heater. You will almost certainly have a higher gas bill per month as well. But the water heater will heat just about all the water you need for most applications. If you were thinking a bigger unit like a 2+ person, you will probably be in the 199,000 BTU range. That is enough to heat about 7 gallons per minute to about 105F with an incoming water tempurature of 45F.