You may be right Th, I might be too optimistic. *But here's what I'm basing it on:

The Energy sticker on my current water heater says it will cost $681/year to operate based on a propane cost of $2.40 per gallon. *From another source on tank water heaters I get a figure of $740/year. *Also, my current water heater is 9 years old, and efficiency drops as they get older (with sediment buildup) so it may cost more.

So I assume my current cost is somewhere between $681 and $740/year.

In Bosch's literature the estimated yearly cost for a tankless water heater, adjusted for my propane cost, comes to $460 per year.

We have low flow shower heads, and once our daughter leaves for college, we won't use a lot of hot water. *

So, even assuming some exaggeration in Bosch's literature, I still hope to save at least $200/year, and maybe as much as $280.