The differences between the two units are very subtle. Most people, speaking in mass numbers, end up choosing based on the price or the appearance of the units. The core technology between the two units (picture quality, etc) are similar.
The LNxxA750 units do have a few differences.
While the A650 series will play music and pictures off of a thumbdrive, the A750 adds video functionality.
The A750 also adds a Content Library feature, which has games, recipes, exercising/stretching modules, and some other features. There also is some content available online to download and use (Free and Paid is available). It's a first generation idea of putting unique content in the television itself.
Here is the additional content available for free:
The A750 is also DLNA Certified. (Digital Living Network Alliance). As the computer becomes more of a central peripheral to the television, this technology could be useful for some current, and more future applications.
As far as the "Halo" effect, it does occur occasionally. Naturally, I can't guarantee that you won't have it, however, we have put measures into place, such as redesigning the bezel from the factory and offering to replace the issue should you run into that issue.
Either set would be a great set to have.
I hope that helps.
I'm back with more questions about the 46" A650 vs. the A750 LCD. I'm having trouble deciding between the two. With the way these units are being discounted, there is no appreciable difference in price between the two (about $60), so the price is not making the decision easy.
One would think that the A750 would be the "better" unit, but I've read a lot of the postings on this forum, and this "halo effect" scares me, along with other concerns about setup.
Are the bells and whistles of the 750 useable to the average (read non technocrat) user? Can you turn me on to what I might be missing if I purchase the 650? Is one unit clearly superior to the other from a feature/construction/durability perspective?
Thanks for the advice!