I don't think there is a Liberty nightly based off .595, they jump from .591 to .596 which was the OTA.
You might want wait for a final release of any ROM before flashing, specially if you have no SBF access. Even then there is still a much higher risk you could end up with a shiny paper weight.
Actually if you can't SBF, I wouldn't try flashing the phone at all. I've bricked my phone several times flashing final releases of many different ROMs, including Liberty. You never know what can go wrong. Just because it's a "final" release doesn't mean you won't have trouble. I wouldn't take that chance. You have a more than insignificant chance of ending up with a paperweight, and without a backup plan (SBF) it would turn out to be a very expensive paperweight.
