Tankless Hotwater Heaters

Are Tankless Hot water Heaters Worth Using? My answer is yes.

The following are the benefits:
1. They are highly efficient, and exhaust and combustion air is from the outside (little chance of CO buildup).
2. They use no energy until hot water is needed.
3. They have a longer lifespan than a conventional heater.
4. The units make hot water as needed, so you should never run out of hot water.

Drawbacks:
1. The expense. Standard units cost $1200 installed.
2. The units require a flow rate of .5 gpm to turn on. If you need to brush your teeth with warm water, forget about it.
3. Multi Unit systems and recirculation loops require much fine tuning, sometime void warranties, and are prone to Cold Water Pockets.

I have put over 30 units in my homes over the past 5 years. Have worked through a number of bugs in multi unit systems. I would like to know other experience's with these systems.