About a thousand and all the same. AGA is barely scratched. Most AGA demos rely on accelerators. There aren't many plain A1200 demos out there.
Using an accelerator is the easy way out, pushing the limits of limited hardware is the oldschool demoscene way.
And hwy? because it's more interesting and groundbreaking to make a limited machine do more, than a less limited machine do it.
If you think something like Rink A Dink Redux is "just another A500 demo" I really have not much else to say.