Does/will CrowdRender involve Cycles Viewport rendering support? I have a second machine with a graphics card but it isn't my preferred machine for working on - boosting viewport performance would be very helpful, but would be difficult to implement depending on how you've implemented the communication between master and child machines.
Another somewhat unrelated question is what data is sent between machines at what time? Are meshes stored pre-emptively before render time on the child machines? Are full images passed back to the master from children, or just individual groups of rays? I don't know the details of how cycles handles all that but was curious how it is implemented here - would allow for interesting new features.