I tried to use once the consisten hashing algorithm in a plain and simple way as it is explained in your slides. I just did set configuration and experienced a problem.
If connections are not persistent, every time Memcached connection is created (lazy although, on first attempt to use any API function) libmemcached C library internally builds in memory the ring structure for consistency. This takes some time.
For our case with around 20 servers it was taking about 500 millis for every time connection is created which is on every request if connection is not kept persistent.
I don't know if this is regular behavior and if I'm expected to use persistent connection in this case or I did something wrong? Persistent connection comes with other complexities though.