As we all know, Octane is great.... on day scenes. When it comes to dusk/night images it's a completely different ball game. Just as an example, it took me 3h to render a 8k pixels wide day scene with very good quality but then the client also requested a dusk/night version and the nightmare started.
As I didn't wanted to manually convert the scene to vray (and use vray... ever again) it had to be Octane. So far my best estimate is 100h on 4 x gtx780 (and there is no point on using more gcards over the network as at this res they are mostly stopped sending data over the 1Gb network).
As unbiased will probably stay like this for a while, we need a decent biased option to use as a life saviour.
Another option would be for the network rendering to be faster at higher res and network licences more affordable.
Cheers