I put a built in Honda generator into my 5er shortly after we bought it new. It has less than 200 hours run time on it.
I would think the advantages and disadvantages would be the same. Here is what I have found:
Advantages:
Don't worry about theft
Runs everything in the trailer
Much more convenient
Trade offs:
Louder than the Hondas
Uses a lot of propane
Wife would rather run an inverter if all we are doing is charging batteries
If I were to do it again, I probably wouldn't install an generator, I'd just go with two inverters and the parallel kits.