You are asking why should you spend the money for one of these USED (maybe even abused) generators instead of buying a new consumer model.
If you need to be convinced it is a better purchase by all means just get the generac. I can tell you the reasons I chose the 803a for my backup generator.
1- It is an 1800 RPM, 4 cyl diesel engine. Almost any consumer model is a 3600 RPM gas piece of crap engine.
2- Look at the size of the actual generator head. It is considerably larger than units rated for the same or more output.
3- Flexibility. I can choose single or 3 phase, I can adjust the voltage and frequency and I can see everything that is going on with all of the included gauges.
4- Quality- Look at the type of wiring that is used and the quality of the components. Far exceeds any consumer level model.
5- Fuel. Propane may not go bad but you are relying on someone else to deliver it. Diesel fuel is widely available. if the SHTF diesel is still available from all of the vehicles around, heating oil tanks in homes.. etc Not to mention run costs. If will cost you 2-3x more in fuel to run a propane/NG unit because propane simply does not contain the same amount of energy gallon for gallon.
6- Weight. Almost always, weight is a sign of quality and durability. A couple guys can carry a 23KW generac by hand. Good luck doing that with the 10KW 803 that weighs over half a ton. The 22KW generac weighs 466lbs
7- Prime power. The MEP generators are designed, and expected to run 24/7 only stopping for regular maintenance. Consumer models are rated as standby generators which means they are basically for emergency use only.
8- I am tech savvy and the idea of something I can work on and have control over- it suits me. I do not want anything with a computer in it or something that will kick itself on every time the power goes out or do its stupid exercising to stay fit once a week.
9- Value. You are buying a used generator. When you buy something used usually it holds its value well because someone else already took the hit when they bought it new and sold it. I bought my set with just over 1,000 hours on it, after it has already been overhauled once. With a consumer model it would be about at the end of its life and worth very little. I expect several thousand hours out of this unit and I could sell it tomorrow and make a profit.
10- Design intent. When a company decides to make a product for consumer markets they basically start with a price point and engineer the product to fit within the price. When a company makes something for the military the military gives them a list of requirements of what the item needs to be able to do under various conditions and they build it to meet the spec. Basically it is built to a specification instead of a price.
11- Fuel safety. Diesel is just about downright the safest modern fuel out there. No need to worry about a gas or vapors...etc
If you look on your local craigslist you will probably see a plethora of nice used generators. This would include used commercial diesel or propane units. I would look into one of those too. It does not have to be an MEP. My local listings include many nice Onan, Kohler.. etc generators in the 10-30KW range (and beyond)
This guy basically sums it up...
https://www.youtube.com/watch?v=iEc66BhuzzI
