If you haven't read them yet, I'd go through the thread for the 651 and the 650. As well as the for the ES6500.
I have had the M3D651SV since Monday. So far I'm pleased with it. Some folks have had some issues, but it seems like someone has issues with almost any of the models I've looked at.
One thing I've found that I like so far is the Smart dimming. this feature seems to help dark scenes. Picture quality was actually better than I expected. there is another feature called adaptive luma, that I've turned off as that seemed to cause more problems than it helped.
This is my first LED, I came from a 65inch RPCRT so I'm not sure how this compares with other LED's