I have flashed custom roms since windows mobile days, so i should have a little experience..!
But you can never be sure to flash safely especially with Lg. You can loose your imei, baseband...etc
And now i have kernel crash on my loved optimus g... A demogod kernel crash. I can boot in cwm but cant restore system. It restore boot and then system restoring fails. I can also boot in android and after a few seconds it crashes. So it doesnt stay long enough to be fx recognized by pc to save it. Pc doesnt recognize it even in download mode. I will also try with another pc.
You dont have such problems with htc or samsung. The problems with these phones arent so complicated like lg.
SO NEVER AN LG AGAIN...