I wanted to chime in on the issues. I just got a LN40C530. My panel is a CN03. Manuf: May 2010. Fair enough, this is only the second day i have owned the tv. my thoughts so far are great.
i turned off the eco setting and dynamic contrast for my bluray player. Now. i have tried an xbox 360 directly connected via HDMI and i have noticed NO motion blur, no ghosting, no issues. I have not heard any buzzing at all. I think the quality is outstanding. I have adjusted all the picture settings. it is set to standard, but i have adjusted the color, contact, brightness, etc...
i got a great deal at my local BB. open box unit that was on display. (on display for 1 day) it was $599. was going to get the sony 40EX400, but saw them both and thought this was a better quality picture. I will not comment on audio for this tv because anything i listen to for the bluray or xbox, will be played though my AVR. i agree with an earlier post where one setting is not going to cut it for audio. you will be friends with that audio adjustmen button.
I was happy for the PIP, but not a requirement. in all, i like the TV. time will tell, but i have a good feeling.