Tankless gas Bosch, $500 + $100 installed myself, 5 yr ago.
One shower at a time.
Can take no limit showers! couldn't do before.
My only regret is I did not get the unit with an active damper.
The unit has a 5" stack, open all the time, You can feel the heat loss.
In Michigan, you can't put it outside.
Does not have electronic ign.
Does very the heat controling the temp.
Manual said not to use unit with preheated water.
Has 10 year warranty (15 if pro installs). Most tanked do not.
In my mind, I had trouble justifying the $600, then I found a good high
eff. Tanked was $470 it become easy to justify. Only $30 more.
I would have liked to get the damper/ele ign/solar, but it was $700 + $100.
Could not justify doing so.
Would have liked the two shower unit, did not like the .8gpm min flow. Did not like the cost $1200. Figured I could buy two Bosch for less, that could do more.
Only couple times would it have been nice.
During the summer the minimum flow can be a problem, end up with a hot shower.
You Can run the hot in the sink...
Wife likes it, so do I.
Have fun.