Some 7800's aren't compatible with all 2600 titles (Although via a multicart like the Cuttle Cart II, that seems to cure it for something like Robot Tank or Supercharger titles).
And the perfect output settings for 7800 titles don't match what 2600 titles need, which can result in low Pokey audio for one issue I recall hearing. Some video modifications actually implement a switch to go between 2600 and 7800 modes as a result.
Not familiar with what Best Electronics does, but there's a lot of fine video modifications for both consoles that will push composite and S-Video out. And I remember a component modification and a new RGB modification for the 2600 was just recently announced, which should be perfect with an old monitor or for pairing up with an XRGB Mini.
If they're operable, all they needed to be is cleaned up. Then, I bet they'd keep on ticking for years to come.
Another thing to their benefit, which absolutely riled up a long departed nut around here when I said it once in a Retron 5 thread, is that an Atari 2600 is actually maintainable. When something goes wrong, even an amateur with some patience and a few basic skills can often revive it. If not, there are other people that can.
When the latest clone goes up, unless perhaps there's a bad solder joint somewhere that's within easy reach to reflow, that's game over.
Many 2600 titles are quite beautiful. Pick up Activision Anthology for the PS2 and take a tour of some of its prettiest titles.
Simple doesn't have to mean ugly.
The French still own everything they acquired, besides Battlezone and one or two other titles that were auctioned off when they briefly considered liquidating their assets. Warner Brothers never owned any assets that trace back to the original Atari Inc. or the subsequent, post split-up Atari Corp.
It's the assets of Atari Games that largely falls under Warner Brothers ownership today. This is the arcade division that stayed with Warner Communications in 1984 after the home division was sold off (Although earlier arcade titles stayed with the home division and went to Jack Tramiel, which is how the French were able to sell Battlezone off). Warner kept the manufacturing facilities for arcade titles, the programmers, the distribution and servicing network, etc.
They proceeded to release many famous titles like Roadblasters and Paperboy, had a home division of their own called Tengen (They couldn't use the Atari name at home), and then sold it in 1996 to Midway where it joined the Williams and Bally Midway coinop libraries. Last title was California Speed before being renamed Midway Games West, and was eventually shuttered completely in 2003.
Warner Brothers now owns most of Midway's IP, although plenty of it went in different directions like Hydro Thunder to Microsoft and NBA Jam to Electronic Arts.