Hi Daniel! Thanks for the feedback! For Ps specific requests/feedback, it’s best posted directly to the official Adobe Community Forums. Please refer to the link @shebbe posted for basic info on how to use it, as well as a place you can leave feedback on the features.
Just for anyone else coming across this thread I’ll try to answer you questions here, but please send further feedback to the Adobe forums.
Regarding defaults, you can manage them in Edit > OpenColorIO Settings. The initial value for the default working space tries a few different roles before just using the first item in the list, and currently the first attempt is ‘compositing_log’. But once you change the default colorspace in the settings in this dialog, it will stay the default going forward. We currently ship with the built-in OCIO ACES configs from OCIO v2.3 (config v2.1.0).
The Edit > OCIO Settings sets defaults for new documents, so you can change your default config and working space for new documents there. OCIO documents are fundamentally different than traditional Photoshop ICC based documents, so the recommended way to open a document with OCIO enabled is either File > Open as OpenColorIO to open an existing file, or create a bland document File > New OpenColorIO and then place your layer. Using ‘Convert to OpenColorIO’ is not the ideal workflow, it’s just there in case you already have an ICC document you want to switch to OCIO.
Placing layers as smart objects is important, as it allows you to set the IDT in the properties panel, where rasterized layers can no longer dynamically apply the correct IDT. Using Open as OpenColorIO automatically automates creating the document of the correct dimensions and places the image as a as a new layer. You can then click the layer, and in the properties panel, select your IDT.
Additionally, it’s important to ensure the display is correct, on most Mac displays, ‘Display P3 - Display’ is correct.