Couple quick and dirty comments on the new 51F5300, after having spent a few hours with it, right next to my trusty 4500, exchanging sources and such.
PC Monitor Functionality --This baby is razor sharp when connected via HDMI to a PC outputting to 1920x1080p. Motion of windows, mouse pointer, etc. are spot on with nary a hint of blur....impressive, but not unexpected.
Magenta/Pink on White / Uniformity Issues -- Or complete lack thereof, I should say.
Using the Win7 PC I had connected to it, I created some full screen white backgrounds and maximized white windows looking for any discoloration or distortion on the screen in a dark room. Try as I might, I saw nothing out of the ordinary, just white. Nothing even close to the pink hue I spotted on the 60" floor model at BB. Same goes for the 4500.
Input Lag-- I fed the 5300 with a component 240p feed from an emulator on my Wii, splitting off the Y(Luma/Green) to my F4500 and tried a couple quick games in which you have a character jumping. Looking at both screens, the motion seemed identical on both. This is a valid test because when I did it with my F4500 and a 20" CRT, I could fairly easily see the lag in the 4500 compared to the CRT when the characters would jump--even though it measured only about 32 to 48ms. I'd say for all intents and purposes its identical to the 4500 in this regard.
240p handling-- When feeding the system from an RGB enabled SNES and Genesis/MD through a CSY-2100 clone, it produced a razor sharp image, quite a bit sharper than the 4500, without the ever so slight pixel distortion on horizontally scrolling backgrounds that is present on the 4500 (because of its much lower horizontal res, undoubtedly.) The N64 was also tested, and ironically produced a very similar image to the 4500, perhaps just a bit sharper, but not as sharp and harsh as my Panasonic 50X60. I'd have to say the 4500 looks a bit better with N64 stuff, the 5300 has a slight edge with the SNES and Genesis however. (Because of the scrolling, in my opinion).
480p handling-- Ran Super Mario Galaxy on Wii to check it out. Actually looks pretty good I think, but in my opinion the 4500 is the clear winner here. The image on the1080 set seems a bit more blurry on the edges of lines / etc than the 4500 does, but its not a deal breaker. If the 4500s 480p is a 10, I'd rate the 5300s as an 8.5 or 9, its still quite good.
OTA HD Content-- Had some HD recordings on my OTA DVR that looked astonishingly good on my F4500, so I connected it to the 5300 and played back several programs/scenes that caught my eye--particularly the NBC coverage of the French Open tennis championships and an LPB HD program about the Japanese tsunami. I'd say it looked pretty damned great...if I wasnt so spoiled by the 4500! Seriously, it DOES look good, but I can detect the slight blur of upscaling being applied to the 720p/1080i programs I viewed. One positive is that it seemed to be able to resolve just a slight hint more detail of small lettering on signs at the French Open, but the overall image to me just did not look quite as sharp, especially when up close to the set (4' or so). When viewing from 6' or more however, I found the slight upscale blur pretty much unnoticable, with the image looking very similar to the 4500.
Overall Pic Quality vs. the 51F4500-- I may catch a bit of flack for saying this, and perhaps part of it is because the panel is spanking new and not broken in yet, but at least for OTA HD program viewing, the 4500 seems to produce a sharper, more vibrant image. The colors just seem to jump out of the 4500 more. Granted , the 5300 is not broken in yet, so the deal with the colors may change later, hopefully it can match the 4500 eventually, but at least for the little while I played around tonight, its not quite there yet. I will say that the 5300 seems to be less prone to visible dithering on blacks than the 4500-- it produces some pretty pure blacks, but I'm not so sure that its not crushing blacks just a little because of that. I'm not a pro calibrator by any stretch of the imagination, I'm just shooting from the hip in saying that.
That said, when watching HD content from 6' back or more, I find the two sets to be remarkably similar, but seeing what the 5300 is capable of up close just makes me appreciate the 4500 that much more-- the 4500 really is unbelieveable for the price. Other than requiring 1080p for PC use (even though 1280x720 is perfectly usable on the 4500) , or watching 1080p Blu-rays, its my opinion that the extra $150 for the 5300 over the 4500 is not really worth it. Granted, as I get to spend more time with the 5300, break it in, and play with settings, my opinion may change, we'll just have to see. For all this talk though, I do believe I'll keep the set rather than return it for a 4500, as I basically got it for a steal @ $495.