Ok, here go a few points
1, KW does not equal KW does not equal KW. The KW ratings on the import built generators you find in the big box stores and sold to residential customers is often "peak" output levels, Lets say 10KW with a surge rating maybe 10% above that (11KW) and a continuous rating 10-20% below the advertised numbers (8-9KW), in reality even these numbers are very optomistic . If you move into the better industrial generator models such as those built by Cummins/Onan, Kohler, etc. you will find units advertised with similar 10KW "Standby" or 8KW "prime" ratings, the difference is they mean it, standby means up to 500 hours per year, prime means day in and day out for weeks, or months. In the case of the Kohler "Fast Response" series they are guranteed to provide 300% of rated output for 10 seconds, compare this to that 10% extra surge rating on the comsumer junk. Then you get to the miltiary units, these units tended to have a somewhat different design philosify of it is better to have a unit that runs poorly than a unit that does not run at all (manual adjustable voltage if the voltage regualor fails, less responsive voltage regulators that fail in full voltage rather than no voltage mode, safety bypass switches on the larger units, etc.) they also tend to have another degree of conservitism in ratings than their civilian counterparts.
2, Keeping in mind the information in topic 1, Determine your reuired load, go throough your house looking at those pesky data plates on the things you HAVE TO power during a major power outage and write down the amps and volts drawn (if listed also write down the watts), in most cases this will be the MAX draw not the average running draw, but be aware motors and refrigeration compressors can draw 3-4 times their rated amps for a few seconds during start up. (again see that "surge number in topic 1) Once you have your list made up multiply the volts x amps to get volt amps or VA (most real generators will list VA or KVA in additon to Watts or KW and it is a better unit of measure for sizing for technical reasons). Now go back and weed out those things you don"t HAVE TO RUN, list those major loads that you can manualy load share by not running both at the same time and list only the higher draw item (washing machine & electric water heater vs. Electric clothes dryer vs. electric stove) Take this number and go back to topic 1 add correct amount of conservitiism to the advertised rating and move on:
3, Pick a fuel gasoline, natural gas/propane, diesel this can be a whole topic in itself, but here go a few points
Gasoline, is commonly available until everyone wants it, then post disaster the nearest open gas station may be 150 miles away. Gasoline does not store well, you must add stabilizer if you want it to last over a couple of months, and if keeping a large amount on hand there is a considerable explosion danger.
Propane, has much the same problems as gasoline, but stores somewhat better, on the downside can you say fuel air bomb if it leaks.
Natural gas, hey it gets pumped to your house which is good as long as the pipeline stays up and you don't have to see the fuel bill at the end of the month.
Diesel, stores better than gasoline, will not explode under normal conditons it will not even burn without a wick, diesel engines are have a far more linear power curve at constant rpms than gas/propane spark ignited engines (at half load they burn about half the fuel they do at full load)
4, Will the neighbors complain, most of the MEP units you will find are not exactly quiet, the hearing protection required stenciled on the side is your first clue, even the little 3kwn MEP 701A (MEP 016B in an ASK (sound suppressing) housing) has a hearing protection required within 15 feet warning, the common non sound suppressed MEP 002's and 003's are MUCH LOUDER, so unless you can locate one at least 50 feet (preferably more) away from where you plan to sleep be aware of the issue.
5, One advantage of these military units as well as the older industrial units is their weight, a 3KW MEP701A is 525 pounds, a standard MEP-002a is around 900 and the MEP-003A is well over 1,000 this makes them unlikely to grow legs and walk off during the night.
As to your question about the condition codes on GL, from my experience the condition codes are USELESS, I have bought 3 generators (2 industrial models and the one small MEP701A) from GL, 2 were listed as HX (not worth fixing), the other was listed as serviceable. The HX listed MEP701A started with just fuel and a jump start, it does have a small oil leak from the oil cooler (bought a replacement cooler on ebay for about $40 and a new battery for about $85), the large HX code 125KW Onan needed a new control circuit board, and a new relay that had shorted because of a bad ground point (about $400 to fix), the fair condition Kohler 30KW unit was far from fair condition as the engine had filled with water (I drained about a gallon or so from the oil pan) and had seized, I was able to free it up by soaking with a mix of fluids, and it runs good, but that was LUCK. I have also bought several other items listed as GX or scrap with nothing major wrong ($12,000 18 month old large HP color laser printer for $300, just needed a drum cartridge to get running), an electric walk behind forklift code HX with a broken fuse holder, etc. SO what it comes down to is buyer beware and trust what you can see in the photo's (to some degree)
Ike
p.s. don't forget fuel consumption, a 3-5 KW diesel generator will consume .5-.75 gallons per hour at full load, a 10KW unit around 1 gallon per hour, 30KW around 2.5 gal/hr etc. this adds up fast in a multiday outage even for a smaller unit your looking at over 100 gallons per week.
