Just a comment from a Samsung F96 user here.
Firstly, I have seen the LX508 at Lakeside in Marlow before I bought my F96, it was VERY good, the colour and depth of black was truely stunning. This would have been my first choice if it met most of my criteria - price, power consumption and value for money.
At the time of choosing between these 2 screens (around January 2008), the F96 was going for ÂŁ2400 and the LX508 was ÂŁ3300, so that was 1 to the F96. LCD is always known to be better with power consumption, so F96 was the choice again and finally, the LX508 didn't come with speakers, so as you can guess I went for the F96.
Rather rambling on, the F96 is pretty amazing in itself. There are a lot of settings to do, and only recently I have tried to change a setting in the service menu which has given a new life to the TV (note, this suppose to void the warranty). This has given the blackest black you can really have (I watch movies in the dark and the top and bottom strips virtually blends into the flush panel). The contrast and sharpness from the pictures are nothing short of amazing. My friend who has a G7 Pioneer was totally gob smacked with the picture quality (this is a bit unfair as his TV is only HD Ready).
I've connected my Sky+ thru the Onkyo 875 which upscale the SD signals to 1080p, some of the channels - BBC, Sky News are upscale very well, while others are not so good (garbage in garbage out I suppose).
Any complaints? Yes, I find the remote response extremely slow on the F96, nothing slick like the Pioneer or Panasonics I have used before, but I have bought myself a Logitech Harmony 885 and that helps!! I've also found that some pictures look grainy, this maybe to do with the actual movie as I don't see the same problems with others.
Overall, I'm very please with the F96. If money was no objection, would I get the LX508 instead? Possibly, but I would have to REALLY justify the premium that the Pioneer holds. I'm quite savvy when I make big purchase, the ÂŁ1000 difference has bought me my new Onkyo 875 and the auto wall mount, so it made more sense to me.
Without having both sets side by side and calibrated properly, it's very hard to comment each, but I could firmly say that the F96 is close, if not equal to the LX508 on the black.