I was at the check out line after Sandy buying a 12 or 15kw whole house generator, and left the store without paying.. after weeks of reading, and researching - for me - and for most people, it's a waste of money unless you REALLY need one, or have the money to blow..
All too often, you can read hundreds of stories online, whole house gens will run enough to do their weekly/monthly tests, and do the few hours here and there when power goes out under normal circumstances.. but TONS of people spend up to 10 grand getting these installed, and when a major storm hits years down the road, and that gen needs to run for a week or two - they have failures.. then the homeowner is left with an out of warranty gen that requires service in the time of need, and you have to wait for a REALLY BUSY service guy to come, diagnose, then wait for parts, then wait to have them installed - and by the time that happens - youre handed a 2 thousand dollar repair bill after your power is already back on, and you scrambled to buy a HF or HD portable unit in the meantime..
It's your money, spend wisely - but I suggest a Kohler over a Generac. That said - your u can literally buy a bigger $500-$600 generator and leave it in the box unused for 5 years - use it for a week straight - throw it away, and still be ahead thousands.. it's all a matter of your personal needs, wants, and what the convenience is worth to you. For me - I just couldn't bring myself to spend that kinda money after much consideration.. I bought a $35 replacement carb for my 7200 watt ETQ generator instead.. 10 minutes and it'll run like new if I need it to.