The burden of proof here is on Cycles. There's 30 years of history showing off Renderman, and everybody in the CG industry knows that it's awesome. Not many people have even heard of Cycles. What movies have used it? Why is it better than the existing rendering software? Is it compatible with the Renderman spec? How easy is it to set up a render farm with it?
This. In theory Cycles can be used to make the same kind of movies Renderman can. Please name a few examples of cases where this was done.
On the flipside, when people say Renderman can be used to make production level stuff, they can point to literally any film with CG made in the past 25 years as evidence.
