Best solution so far. The only draw back is for the clients that are not communicating to the server - they will be gone unless they get a successful connection in the future. I recommend that you export a Computer Status log first so you'll have a list of clients before the cleanup.
I used to manually delete these clients on my spare time. Export a list, then sort by hardware ID, then by IP address, then by connection date (descending). Then use the search option in the clients view. And manually delete. Very time consuming.