Maybe a more relevant piece of data is the rate of ECC errors in servers with ECC memory but, as discussed in the post, my experience consumer vs. server CPUs, RAM, etc., is that server hardware is more reliable than consumer hardware, so extrapolating from the observed error rate in ECC memory won't really get you to the true error rate.
But even so, from the server data I've seen, which would be overly optimistic, I would not want to have servers without ECC.