Why does raytraced take so much longer on Mac?

[John_Brock]

Yes.
WIP/BETA development builds are available to anyone that owns a paid license for the current shipping version:

Welcome to Serengeti

Serengeti, named after the largest African Savanna, is where Rhino grows. We like to involve users in every phase of the Rhino development process. As with prior releases, we invite current users to try, test, and provide feedback on the next release while still in development. You can now participate in the development beyond the upcoming release. Since many development efforts span more than one release, we have set up the Serengeti Project to give users more direct influence on all future …