The MRC Orca is by far a better skimmer in my opinion and would be much more consistent with less fiddling. That said, the Reef Octopus will be MUCH more efficient and more quiet due to the fact that the Orca uses a beast of a pump compared to the RO. The Reef Octopus on the other hand will need the pump cleaned regularly (monthly or bi-monthly) to remain nearly as consistent as the Orca. While the SRO does have a larger diameter body, the Orca uses a beast of a pump that will generate greater air flow and finer bubbles. Don't get me wrong, the RO is a good skimmer but the Orca will outperform it in my opinion in large part due to the pump it uses.
If I had to choose between the two and power consumption and noise wasn't a concern, I would choose the Orca over the RO in a New York minute. If power consumption and or a bit of noise is a factor than the RO will work just fine.