Wanted to throw in my 2 cents. I purchased a pair of CPE2000i boxen in 09/2010. (They have a build date of 07/2010) They did double duty as backup power to my home, and as tent camping generators. In their backup power role I always had trouble with these generators once the power draw reached the 2500-3000Watt range when they were parralled. My fridge would kick on either the compressor or the defroster and they would overload fairly immediately. They also have a slight throttle hunting issue at 1000-15000Watt load parralleled, but not at idle or full load. (Weird and irratating!) Well I recently purchased a pair of yamaha ef2000is generators to replace the cpe boxen. The CPE engine is indeed a close copy of the Yamaha, so much so that the parts look interchangeble by eye. However the ef2000is is a different animal concerning the inverter hardware/software and output performance with eletrical loads. In the home backup role a pair of ef2000is gennys will sustain 3600watts with no overload light, and I can confirm the 1900 watt peak per unit 20second cuttoff. As a test I dropped the entire 3600watt load onto the ef2000is pair running in econ mode as a unit step function. At first the voltage sagged some but they spooled up (took approx 5 secs) and held the load with no overload light (econ off the voltage hardly sagged at all). The same test with the CPE boxen would result in an overload immediately eco or not eco. I lowered the load to drop 3000watts and then 2500 watts on the CPE twins, they still overload eco or not. They are not very tolerant to surges.
The yammis are to my ear a couple of db quieter than the cpe2000i's at both idle and full load. They do not hunt at any throttle setting either. I don't think the CPE gennys are bad boxes, they run well within their performance envelope, but from my experience that envolope is kinda small, the throttle hunting and the low tolerance for surges and high loads is very irratating. Is the 1800 I paid for the yammis worth the increased performance? In regards to their superior load handling I would say yes. The small increase in quietness, not really.
