Memcached as Session Handler

Hey list, I run a website that integrates MemCache, MySQL, and PHP sessions very heavily. I recently came across some documentation on the PHP site that informs me that I can use MemCache as the session.save_handler, instead of files. I know there would be no redundancy of the session data with this type of setup, in the event that the MemCache daemon fails. However the website is run on a single server and a single MemCache daemon, with a single IDE HDD. I'm curious as to if anyone else uses MemCache as the session.save_handler? What are the pros and cons of doing this? I figured it would help out with disk I/O and overall performance because MemCache would be much faster than the IDE drive, and I update/reference the $_SESSION data very often. Thanks!