Grumpy, I didn't "forget" standby losses, they are factored in to the already metered 12 therms per month operating costs of the tank-type heater. In other words, if I used NO hot water I would STILL have used gas for the pilot AND for keeping the tank hot.
Also, your factor of 1,000 BTUs per cubic foot is NOT exact. Natural gas piped to a home is a mixture of gases and while 1,000 BTUs per cubic foot is an easy number to remember for approximate usage, the gas company multiplies the cubic feet consumption by a "BTU correction factor" to arrive at the number of therms you are billed. This correction factor is listed on the gas bill and changes on a regular basis.
Now depending upon the individual gas supplier a cubic foot of natural gas might be a little less than 1,000 BTUs, a little more than 1,000 BTUs or exactly 1,000 BTUs during any particular billing period.
That isn't what the tankless proponents would have a person believe. In fact, it seems to me that a "small" (i.e. single person) household should be more suited for tankless because it is more likely that hot water would only be used at very specific and infrequent times and using tankless in this situation could definitely reduce the losses from tank standby operation.Tankless isn't for small households,
It is obvious that you have "bought in" to the arguments given by the tankless manufacturers hook, line and sinker. Now if only "they" would enforce truth in advertising we all would be in a better position to judge the relative merits of each type of hot water supply.