The main benefit is being able to see the Renders as they render. We render a high number of renders and the design is usually changing to the very last minute. Obviously with our renderfarm we can check the progress of the renders, see if everything looks ok, cancel renders, stop renders early if we think the noise limit is enough etc. Basically we are looking for that same level of control.
From what I can tell Chaos Cloud is the only farm that allows you to actually see the image as it is rendering? All other cloud services you have to wait for the image to be fully rendered to see it. Though maybe this is incorrect; We've only used Rebus farm before so happy for suggestions for other cloud rendering services.