Gut instinct says photo reduce then manual shuffling about. Too many pixel clusters a computer would consider good ideas but a human being not, but you can never be sure. And is it so important to be 100% sure? This art would benefit from a finer pass in pixel precision but that has little bearing on what it means to you, if anything. It's not masterpiece-craftsman quality if it's straight-pixelled, it's not masterpiece-computer-reduction quality if it's computer reduced, so in that middle area, why is it so important?
The second link doesn't work.