I didn't actually benchmark with 'benchmark' - but on practice, I am running a local p2pool node and it gives all my local machines jobs and forwards to the p2pool mini mining pool, I just type status on my p2pool instance and it gives me my hashrates (low right now because wife is using the other computer and I have it set to pause on user activity)
Yesterday I was hovering around 17-18k hashrate on 4 local workers.