I own a general 14kw emergency generator and run it on propane from my home heating 500 gallon propane tank. I have had the general for almost ten years now and other than service and maintenance I have had no complaints! I installed the emergency generator and the required switch myself with little to no issues! I suggest what ever system you eventually buy you buy multiple maintenance service packs and keep the, on hand doing the service as recommended! My generator does a 15 minute self test each Sunday as I had programmed it to do! I believe you can still but the 14kw for about 4K and the 20 K for a little over 5K. Good luck and I don’t think you go wrong with either system!