Yes you can use ACES OCIO config in Blender, but...
@troy_s don't hesitate to correct mistakes or add infos to what follows.
I've just try it since 2 days, I've seen the new ACES 1.2 OCIO config pop up and decided to give it a try. At the begining I was quite enthusiastic, made some tests, more saturated, ACES config need adapting color values.
Since you can't change the colorspace of the color wheels, they are going completely crazy, click on a color of the wheel, then in HUE change the saturation, or click and drag on the wheel, it speaks for itself, if a dev read this, we really need to have color managed RGB color wheels as well as a better color picker... if we want to work with other colorspaces.
Knowing that I thought, ok I know this limitation, so I can be carefull and use only RGB channels to set my colors (a pain but I've tried it and managed to make an ACES test scene)
I was quite happy with the render result even if it looks a bit too saturated and then I realised that the glossiness looks less present, perhaps it's like Filmic that looks to desaturated at the beginning because we weren't used to it, for this part I don't know if it's something expected and normal or not.
However, today I've made tests with a chart image to see if it is correctly interpreted.
Images aren't correctly converted. I have this sRGB chart as a base to see what a transfer from ACEScg color space to sRGB should look (sorry I never know if it's EOTF or OETF):
A screenshot of the convertion from ACEScg to sRGB, we can see is that it don't react very well:
Even in Resolve/Fusion it's not 100% correct:
I don't know if the color difference is a big deal for a normal scene, but it makes me doubt that it's a valid workflow inside Blender, for now. If someone see a mistake in my test let me know.
I will perhaps try a real scene to confirm all of that, but looks like for the time being, there is nothing better than this great Filmic OCIO config we already have.
In fact all of this makes me think that I understand a bit better my fist test with ACES.
I've made a simple scene only with shader colors, no textures, resulting in an oversaturated image.
What made me thought that, like Filmic at the begining we would have to adapt a bit the workflow, but now that I look at the wrong desaturation of the bars of the chart, it feels normal that I have an oversaturated image, and that it's not a workflow to adapt but that I'm fighting a wrong colorspace convertion.
The filmic scene:
And the ACEScg verions:
I've just understood some fundamentals things, and then read Troy's comment that confirm it.
I've made mistakes, and like he said I've learned a lot from them.
I will surely make more but perhapse all of this will help other to understand this so complicated topic.
What I've just realised is that ACES OCIO config doesn't map primaries to rec709 ones, it clamps them. So the desaturation of the top horizontal bars can't be something else, in fact I've ask someone to try with an other render engin (he tries with Guerilla render) I was shocked that it was the same.
And what we see on my test scene rendered in ACEScg is just that, clamped gamut, a bit like the clamped intensity of Blender's standard(sRGB) view transform but with gamut.
One other thing I've realised is that wider gamut isn't about having better color display on a standard monitor but having more colors to display to a wide gamut monitor and surely internals calculations. Perhaps it looks obvious but this topic has so much confusing part that I was thinking, converting from a colorspace to an other was also to match primaries from the first one to the other but it's not what ACES does.
So, can you use ACES OCIO config in Blender, yes, would I use it to have better images than with filmic, hell no. Even if Filmic isn't perfect, I think it's still better than to fight clamping gamut, unmanaged color wheels... and I don't think the cases where you would see a gain compare to Filmic worth the pain.
If you need ACES it's for other reasons.
I'll surely add more stuff here later when my knowledge grows, or perhaps add a new question on Stack Exchange, like for exemple converting rec709 values (or pointer's gamut ones) to ACEScg colorspace.