Anyone that's seen Level II OS-9 on a Color Computer 3 (or the 68K version) would have to admit that its an unusually powerful OS (if somewhat intimidating since it can do some scary things via CLI).
I was a color computer guy before amiga... I had like 10 color computers over time. I still have 5 of them. os9 blew msdos so far out of the water, I used to dial a bbs, play a game while downloading files, render fractals, and play music files all at the same time, and that was in 1988. I had a pc too at that time (A 286 I think) but the coco was much more use, especially for fun stuff.
I switched to a friends pimped out amiga 1000 next. Being so used to multitasking, I couldn't stand a pc as my main computer...
I still use color computer 2's and 3's for hardware projects, because they are so easy to interface too. I have an alarm system built from a coco2, and a home automation controller built from a coco2. I have also built a bunch of robot projects using the coco2's or 3's because it draws less than 1amp.
Besides amiga, color computers were and still remain one of my favorite computers... I learned to program in basic on then, I learned to do hardware projects on them. Mostly, I learned how to push a computer to its limits and beyond on them.
I have seen this atari 6809 project and yes looks interesting. I am still on the coco mailing list... Which is quite active.
Steven