Hi Goldis,
why are you so angry, what if you were to work with inches?..
If you will have to work on a ship 3D model, produced in the US, do you ask to developer to edit it in mm?
I have repeated a thousand times you can work with mm cm m km, this has no effect with unit set in mt.
I do not understand what the problem is. Is it so hard to accept Octane think in meters? It sounds something like absolute and relative coordinates, where is the problem so angry?
About ray epsilon, I do not consider to be a relationship between absolute ray epsilon and unit scale, its use is subject rather the scene you're rendering, geometry, and distance from the camera. However, in this specific case you are ignoring GI.
https://youtu.be/frLwRLS_ZR0My advice is you could make your own presets Octane about kernel etc and save them (setup Render> preset).
Regards
Paride