I put in the base model Bosch (gas) two years ago.
It was about $400 at the home center.
The "high flow" model runs around $900, the difference is that the model I got willonly run one "major" line at a time. Translation, it wifey starts a hot laundry load while you are in the shower, you hot water flow rate drops by about 75%. It simply won't make enought hot water to run two things at once.
Upside, though, is that, knowing you have to run things one at a time, you can take a HOT shower .3 seconds after the dishwasher ends, the sixth load of laundry, and every female in sight took their showers, it simply NEVER stops making hot water while the flow is going through it.
For our purposes, I didn't spring for the high flow model, and I don't regret it.
Water at the tap is HOT, certainly as hot as with any conventional heater.
Install was pretty striaghtforwad, except that the water inlet and output are on the bottom, so is the gas line, so there was some more plumbing involved than simply swapping like a standard tank.
ALso, there's now a TON of room in the hot water closet.
I give it a 9 of 10, not sure why it's not perfect, I guess nothing is.