We observe that anti-aliasing is not working well for transparency background (transparent parameter set to 1) as you can see:
with some background color you will see it more precisely:
and the same model without transparency (transparency parameter is 0):
You can see more models like that at our page: http://www.termaheat.pl/pl/3dvisual
It look's like that for transparency background the anti-aliasing for edges is not enabled or it is working just at 8 bit mask. Could you check it ? Please.