We do support mutli-core systems, and will take advantage of most of the CPU processing power when transcoding to different deliverables.
Cortex is designed to maximize the speed of encoding each clip, so you’ll likely see that the CPU usage is quite high when doing a single transcode. Rather than trying to run multiple processes at a time, a single process is multi-threaded.
Doing multiple transcodes at a time would slow down each process since they would take resources away from each other, and the overall throughput would not increase.
One other thing to note is that with some formats, most of the work for decoding the frames is done on the GPU (and ARRIRAW is one of them). So to achieve the best performance for the case you mentioned, we would recommend running on a system with a new, fast GeForce card like the 780ti.
I would recommend running some tests to see whether the throughput of a single system meets your requirements, and if you really do need more throughput than a single system can offer, you should check out the Enterprise Edition: