The gen 3 is a big step forward from the earlier units and much better than 95% of the tank type heaters on the market.
(Why 95%?...any tankless unit other than the Truma cannot supply repetitive amounts of hot water. Think about washing your hands, or better yet, doing the dishes. You turn on the hot water, wait 10 seconds, get hot water, do the wash or rinse and then turn it off. 5 seconds later, you turn on the hot water, wait 10 seconds and then hot water appears and you wash or rinse. You must wait that 8-15 seconds every time you turn on the hot water for the hot water to show up. This does not happen with a tank-style heater. But-for taking a shower, you wait 10 seconds and then have hot water as long as your water and propane last. Just don't turn it off.
Some larger, 10 or 12 gallon tank style heaters with quick recovery can do a great job of supplying repetive amounts of hot water and provide a pretty lengthy shower (just not unlimited however) These larger water heaters are not so common, so that is why I said 95%. The Truma is truly the best of both worlds, but as you found out, can be costly to install. I like our gen 3 Girard very much but since it was close to $1000 to install with labor, I might have chosen the Truma if I had to do it over again. Using a tankless system when the outside temp and water temp is down near freezing can be a challange, but that is another story...)
St. Charles, MO
Ex-SF Bay Area
'99 Ford E350 V10
'16 Rockwood 8329SS