How Efficient/Stable are the am-utils?

Steve Baum asks: "I'm thinking of replacing a current tangle of NFS cross-mounted disks with the am-utils system, which maintains a cache of mounted filesystems that are demand-mounted when first referenced and unmounted after a period of inactivity. I was wondering if anyone had used this system in a moderately large (40-50 disks on 10-15 machines) environment and, if so, how efficient and stable they'd found it to be."