99.999% of the software we can run on our servers can be run on a Mac, it's (arguably) more user friendly than Linux. They're also pretty decent spec'd computers that take a while to go out of date (My 4 year old MBP runs Lion with no problems).
I heard that Lion was shipped with a few issues and have heard a few people wishing to go back to Snow Leopard. Is Lion a step backwards?
New software will always be shipped with bugs. If You haven't urgent need for Lion I encourage You to wait until 10.7.2
There are a few issues, particularly with LDAP, but that wasn't what I meant. Lion is the latest version and it's running fine (minus the bugs present on every system) on 4 year old hardware.