[Mikendebbie]

I should probably PM you to avoid drawing fire - but we have a Suburban IW60 and it has worked well for us. I had one issue...September 2021 (~18 months into covid shutdown) we were getting ready to go on a 2 week trip. The Monte had not been used since December 2020. I was testing things out and the water heater did not work. Could not find much help on youtube to troubleshoot. I asked DW "Honey it will be just like when we were in the popup - we can use the campground bathrooms". The answer was "NO WAY!!".
So I pulled the trigger and ordered another one for $600 and installed it. The old one is in a box. Later I found a video about cleaning out a probable spider web in a certain orifice. Oh well - now I have a backup!

The install is easy - old wires hook up to new...control wires hook up easy...gas and water in and out - easy peazy. The back of the unit gets a small steel angle to anchor it to the floor. My unit is accessed by removing the basement wall...good access. Whatever unit you choose - make sure the outer cover is included...since your current outside cover will not work - they may sell the outside covers separately.

What the IW60 is missing is the plumbing apparatus/fittings/valves to descale it. I will install this after I retire in July...I have the instructions and the fittings are at Home Depot. For winterizing - I always drain the Monte after every trip. I blow the plumbing out with air. I have had no damage from the recent artic apocalypses and power outages that hit Texas (Feb 2021, Feb 2022, Jan 2023).

I have noticed that some of the new on-demand units have easier methods to descale built-in. LOTS of folks complain about waiting for the hot water to get to the shower head. No big deal for me. I leave it at 129* and temper with cold water rather than messing with the thermostat to get (say) 105* water with no tempering. Our unit has a full tub across the front. DW loves her bathtub. I think with any of the on-demand units - it will deliver (say) 103* water in the winter rather than 115* water because the city water coming in is colder. The unit can only raise the temp of the water so much - so if you start with cold water - the end result will be cooler. Again - no big deal to us.

Edit: screen shots below...
Actual temps I get from my heater from a thread last year I think.
Also pics of what the unit looks like behind my basement wall...red arrow pointing to the steel clip angle.