Would I be correct in saying that the CPU miner doesn't offer anything functionally or increased performance over say mikalh's version?
Yes, because Reaper uses the exact same code.
I would not mind to test at least the CPU version of Reaper today.
So it's a good idea to release it for donators. Can you do it today?
Why not release the CPU miner to the public? The donations were for a
GPU miner, which will still be in a closed beta when it's ready.