Coming from a photographic background the thing I'm really missing so far is a histogram to show the distribution of tones in the image viewer as it renders. Mainly to ensure I'm not clipping values at the highlight end. I'm used to using a histogram to adjust my camera exposure values and it would be great to see one in Octane.
My current workaround is to take a snapshot to the clipboard, open that in PS and check the histogram then come back to Octane and adjust camera settings, repeat until right....!