The Xserve I bought was a fairly older model being a G5 system rather than an intel, but for $300 I couldn’t really complain. I was very happy with Ubuntu and just in case, I made sure that I could load it on the Xserve if I wanted to go back. The main extras that I get with OS X Server edition is being able to fairly easily set up a Time Machine server to backup our laptops over the air and the ability to have iTunes setup to stream media to the Apple T.V.
The other plus is the Xserve is much quieter than the previous server. Which is certainly an issue living in a small area. I would compare the noise to the Xserve to that of your regular desktop PC. I still have a few more things to setup and will do my best to try and document them here.