No argument from me.
The most innovative stuff comes from the C64 scene, which is the only one I'm semi-active in.
I also agree with sticking with A500 specs. If you check last Revision's results, you'll see A500 demos are making a serious comeback
AGA/060 demos can be compared to early Pentium-1 demos.
Many (Most?) of them are "just" C2P based and can be easily ported to other platforms (as proven by Atari Falcon ports of TBL demos).
Still, I enjoy watching the ones that run at acceptable speed on a 50Mhz 060 and don't require overclocking (Hi, Elude...).
Did I ever say that I do not understand this stuff? Frankly, if I want to get the most of a machine, I'll get a PC. If the competition is to get the most out of as little as possible, stick with a plain 68K at 7MHz and get creative. That is the art. Heck, even a 1.7Mhz 6502 can do interesting things if you know how to play it.