Hi,
And the big advantage of separate components is that there is greater flexibility to the way the RV can be powered. Add to that ease of trouble shooting. The parts are also cheaper. (three strikes and you are OUT! lol)
I can plug into a 15 amp service--and still run the RV pretty much as though it were plugged into a 30 amp service. I plug in the converter and the water heater to shore power, and plug the rest of the RV into the inverter.
No transfer switch (which when switching under load may eventually end up non functional due to burned contacts).
This is most useful to me as I often do not have access to the shore power breaker.
Because I finally broke down and purchased a generator (Yamaha 3000 iSEB), I also use the inverter to power things when the generator is maxed out. It's kind of neat to be running 4000 watts from a 2800 watt generator. Granted, I can't do it forever, but I can do it for long enough to get the water heater to full temperature.
For these "tricks" I did "break out" the converter and water heater from the OEM power center. I used standard plugs to do so, so I can go back to OEM in about 20 seconds.