10.7 Server file sharing reliability

We have an old 10.5.8 Server that is running AFP and SMB. It's been running reliably for a long time, and with recent possibilities of departmental changes we haven't hurried to update it until we knew more. Lately this server has been hanging and requiring reboots too often to be acceptable. I'm thinking of upgrading it to 10.7, the latest it supports. We haven't used 10.7 Server for File Sharing so I'm wondering what the general consensus is for reliability and best practices.

It's connected via fiber to a Promise Raid.

It's bound to AD and is not using OD.

We aren't using it for network homes. Only share points for departments and server processes.

With 10.7 Server, how stable, reliable, robust is SMB? Should I install the latest Samba and not use the built-in version? Or use SMBUp?

What are some of the commonly used tweaks (configuration files, etc) to make it more stable, reliable?