M6400 vs M6500, which is better?

I'm also trying to decide between a used M6400 and M6500. I just recently purchased a nicely spec'd M4700, but not really impressed with the screen (FHD non IPS). When I put it next to my E6500 with WUXGA, it just doesn't seem to compare. I was under the impression that the display in the M6400 was still CCFL, and the M6500 was LED. Can anyone who has owned both these machines comment on which WUXGA display was better? M6400 vs M6500.

 

M6400 has LED screen, you even can have M6400 with a RGBLED E2E 1920x1200 screen

 

Or (if you don't like glossy screens) you can even have it with a "regular" RGB LED screen. Supposedly, there were LG and Samsung screens, so the word seems to be that the Samsung on the M6500 was better (I've only had (still do) the LG one on the M6400 so I can't compare them).

 

Yeah, but the problem was that the FX-3800M is just an overclocked FX-3700M (built in a smaller technological process) which itself was still another re-use of the same old G92 GPU, while the M7820 was a newer GPU with much better performance in e.g. 3d Mark 11 (thus, should be better performing with the new game engines).

I've also noticed a certain amount of threads describing problems with that GPU on the M6500 (black screens and stuff, kind of like the problems experienced with FX3600M on e.g. 8710W and newer drivers).