OSX Lion Server vs Client performance

I am using a Mac Mini (current generation) with a Drobo 2nd generation (running firewire 800) as a server in my home. It hosts my itunes shared library, Iphoto library, shared storage and is the server where all of my macbooks write their time machine backups. I have 4 macbooks in my house backing up to this server.

I am running the OSX Lion Client OS. Performance is not great. I find that I get jerky video performance when watching movies that reside on the Drobo. In general the server seems slow.

My question is whether there is any benefit to upgrading to the OSX Lion server with regard to performance? Or are there any other benefits to Lion Server considering what I am doing with it? I have no intention of hosting any wikis or sharing files with ipads or hosting web pages or any of those other functions of Lion server.

Thanks