After using two Sono roasters and several iterations of UFO/CO roasters, I'm of the opinion that the Sono is a simple to operate, albeit one-dimensional, roaster while the UFO/CO offers unlimited roasting potential for the attentive roaster.
The Sono has 10 preset programs, but all have identical roast profiles; with the only differences being the degree of roast. Its strength is that you get a near-identical roast for each batch of beans, with no input from the operator. It's weakness is the total lack of operator control over the roast profile. edited: I've found that some beans give better results in a Sono than others. When I find such a bean I now buy larger quantities for future use.
The UFO/CO offers a skilled operator near-unlimited control over the roast profile, but it requires the undivided attention of the operator to achieve great roasts.
To my mind it comes down to how much attention you can give the roasting process. If you're the sort who can hover over the roaster and have some OCD tendencies, then you can make the UFO/CO roaster sing a pretty tune. If you're like me and just don't have the patience to tweak the UFO/CO's variables, then the Sono is a better bet.