LG dilemma

I'm guessing you're in the U.K., going by the model numbers you cited.. They seem to be the same as the U.S. models 55LM9600 and 65LM6200.

Anyway, that's a toughie. The 960 55" is LG's top model and has full LED backlighting, nano filter, and local dimming. The 480 Hz and dual core processor don't impress me much, although supposedly the latter makes the TV more snappy when changing inputs. Note that despite the full array and local dimming, the picture is not as uniform as might have been hoped, according to this:

http://www.avforums.com/reviews/LG-LM960-55LM960V-55-Inch-3D-LED-LCD-TV%20Review_305/Review.html

OTOH, the 620 65" is bigger and is quite a nice TV. I have a set pretty much the same, the 65LW6500, purchased a year ago. Yes, the backlighting is not perfectly uniform, most visible when you change to an input currently off. Not an issue when viewing a Blu-Ray, for instance. Viewing angles are good, and black levels are acceptable to me, since I rarely have all the lights out in my home theater. If you're a purist about that, like so many here at AVS are, it might not be good enough for you.Passive 3D is very nice, and my set is plenty bright for full daytime viewing. Colors are good and the set has full controls for fine calibration, and I presume the 620 does as well. Here's a thread about the 620:

http://www.avforums.com/forums/lg-forum/1596127-official-lg-lm620t-cinema-3d-smart-led-tv-thread.html

I dunno, after having a 65" set for a year now, I'd find it hard to go with 55". Good luck whatever you decide.

AFAIK, there are no plasmas using passive. Only LED (LCD).

My 65" LG replaced a plasma. Well, not replaced actually, because I still have it in my study. I originally intended to get a 60-65 inch plasma for my home theater, which I remodeled from a spare bedroom a year ago.

I first became interested in LG's FPR passive system because, upon its debut almost two years ago, it was being discussed extensively at videohelp. So I had a look at active and passive sets at Best Buy and was convinced passive was overall the better system. No crosstalk, no flicker, cheap battery-free glasses, plenty bright. Resolution is reduced, but it's no worse than going from 1080p to 720p, which, depending on viewing distance, may not even be noticeable. Native contrast on my LG was 1,600:1 before calibration, not impressive on paper, but in real life viewing, it's not bad at all.

Like I said, I was fully prepared to go plasma again, but I was impressed by the LG I saw. With any kind of ambient light, the importance of black levels can be overstated. And the LG had whites that no plasma can match. Real whites, and no dot crawl or the other plasma drawbacks. It doesn't handle motion quite as well, but its frame interpolation does a creditable job. A nice bonus which wasn't clear from the documentation is that the LG will play H.264 encoded 1080p video in MKV or transport stream (TS) direct from an ntfs formatted powered external hard drive, up to 2 TB size. It will play many other codecs/containers as well. The inbuilt player is the exception to the rule that onboard TV media players suck.

Hey, pick which drawbacks you can live with, as neither tech is perfect. Have a look at both types and compare, if possible.

If you're set on a plasma, look at the Panasonics. Supposedly they're a great set for the money.