AFAIK Atari never used anything present on the Amiga exept the processor.
When Commodore bought Amiga, Atari had to faced 2 problems: they lost the successor to their 8bit line of computer and they couldn't compete with one of their main competitor.
So they had to go fast, very fast: bringing a completely new computer in months, this is one of the reason why Atari used off-the shelf compoment for the ST. When the A1000 came out, the Amiga team was working for 2-3 years on the project.
As you: the demo is neat but misses many other things that made the Amiga the best computer of it's time.
