can I make one observation?
on ST, coders need, as you said "to emulate" (I would prefer phrase "to find way") to achieve Amiga capabilities. One of need was to display more than 16 colors onscreen so Atari coders find a way in 1987.: Spectrum 512 (http://www.asterius.com/atari/spectrum.html
It is nice to see that Amiga coders adopt this idea. as I said before: I want to see how far coders manage to push limits of hardware boundaries
btw "manually Copper can do more (but not more than 50 few changes per scanline)"
- copper will do this with 0% CPU time, and some bus time, right? and one more thing: how much bus time will consume hires with 4 bitplanes on OCS/ECS?