My tests last year showed the inverter was @ 93.22% in actual efficency vs. a claimed 97.6% and this data was part of the behind the scene push to get the CEC to have offical UL observed and cerified performance of the inverters used in CA. The PVP2800 since came in at 94% in the official CEC tests and PVPower was pretty mum on the haircut its inverter received.
The PV powered has since done some improvements but no inverter is better than the GT3.0 in efficiency and the GT3.0 is lower street priced and has more features included to boot
PV power has approched me to test their lastest units but I am currently booked thru next spring with work so it will be sometime before I could even think about doing a new round of tests.
You can look at all the available CA approved inverters at:
http://www.consumerenergycenter.org/cgi-bin/eligible_inverters.cgi
Hope this helps