Keep in mind, the reported efficiencies are limited in accuracy to about 2% ( +/-% ) plus some static amount. The Inverter is not a laboratory power analyzer and once you get over 90%, the measurement errors get to be a larger percentage of the reported values.
Having said this, The GT5.0, has at CEC rating of 95.5%...
http://www.consumerenergycenter.org/erp ... 0GT5.0.pdf
I have been running the GT5.0 since Novemeber, I have both of my 3400 watt arrays tied into it, previously I had a pair of GT3.3's, one on each array.
My arrays are on roof, at 22 degrees and the run very hot here in Florida, the GT5.0 is not maxed out, except for the occasional edge of cloud events
One other note, I'm doing engineering work and regulary switch out part of an array for the bench work, so the generation totals are not 100% of the two arrray