We (Magna-Tel Inc.) have used both Suitcase 7 and ATM 4, but neither of the newer versions.
Personally, I like ATM better than Suitcase. I am in the process of upgrading all of our machines to ATM 4.5. ATM gives you more direct control over your fonts than Suitcase, and you can print a catalog of all of your fonts for a reference.
Just my opinion, See ya,
Pixelbender