Just saw this on the mybroadband forum

"Finally, just for interest sake, here is the output of the Axpert while running from battery and servicing my house (in other words, whole under resistive and inductive loads). It's a fabulously clean sine wive - I'm really impressed with it:"

 

His Eskom wave

"The first one shows the Eskom feed. It's fairly clean, except for a fast drop-off just after reaching peak:"

 

http://mybroadband.co.za/vb/showthread.php/808222-Axpert-MKS-5Kva-inverter-firmware-upgrade

I've avoided putting the scope on my AC at home because it's limited to a mere 250V peak (and AC is 325). But it should not take too much effort to do this using a small transformer, though I'm not sure how the transformer affects the waveform. Apparently, not much... so I'll give it a try later.