These Chinese diesels and generators are low-rpm copies of very old British engine designs. They're dirt simple to maintain, can be completely torn down and rebuilt in a weekend (with shadetree mechanic tools), and have a well-established habit of lasting for decades. They're heavier and bulkier than the Onan RV gensets, are a little less efficient, but the fact that you can fix most issues yourself is a big bonus in my book.

If you are going for an on-site propane system, I would try to refit your water heater, kitchen stove, and furnace away from electric to propane (the fridge can also run from propane http://www.warehouseappliance.com/propane_gas_refrigerators.htm). This will let you continuously consume and replace fuel (fresher fuel), will help you make certain your fuel delivery components in good order, and will also allow you to size a much smaller generator for your household electrical loads.