[AdamTReineke]

Just saw this, I would recommend going the heat pump route.

In retrospect, it's insane to get an electric tankless hot water heater from a climate perspective. Gas tankless makes infinitely more sense if you need limitless hot water. If you don't need limitless, heat pump would be the most emissions efficient.

I'll try to get my usage data together and update this comment.

Edit: Cost of usage electric and gas over the last five years. The big spike last winter was due to our remodel and heating the whole house while it was neither sealed nor insulated in the middle of winter with just the 10kWh furnace backup heater which ran almost non-stop. Units are USD. The two gaps in data are due to meter replacements, I think. https://imgur.com/AVTFwpP

It's kind of hard to compare the data since we re-insulated, went from gas furance to heat pump, and added a hot tub.

[AdamTReineke]

Too late to edit, but on the imgur graph - yellow is electric cost, orange is gas cost.