My wife and I had an Eccotemp 40-H Tankless water heater (Nat. Gas) installed in our House on Dec. 15th...The unit (~$700) and about (~$350) for installation. I ran the electric (15amp GFCI) to save a little money...It is mounted on the exterior of the house, here in SC.
All in all we are very happy with the unit...It freed up some much needed room in our 1500 sq ft house, and we are very please with it, setting the thermostatic contol to 115 is PLENTY hot...we chose this setting because you can basically get in the shower and turn the hot water valve full on, and just crack the cold water valve a little bit.
problem: Location, Location, Location - We located the unit on the far end of the house, about 4 or 5 feet from the gas meter. This puts it a good 40 feet from the washer and kitchen sink (and dishwasher when we add one!) The old tank was on the opposite side of the house, about 35 feet from the full bath...this meant that when you went to take a shower, alot of cold water flowed before it got warm....now, when you go to wash dishes, alot of cold water flows until it gets warm. The pipes under the house are not insulated, and I think that would help to some extent.
We have had no problems with water pressure. Our old water heater was 43 gal Rheem circa 1995, and we were glad to replace it with something more efficient.
a potential solution to our problem is to add a small (10 to 15 Gal.) electric water heater underneath the kitchen sink. the tankless unit would do the heavy lifting (bringing the 'outside' water from water temperature from whatever it is up to the 115 degrees), which is where I believe the modern tanked water heater uses much of it's electricity. This small pony tank would feed the kitchen, laundry, dishwasher, and 1/2 bath (currently being planned) for that side of the house....another option I think would be a small under cabinet electric tankless water heater