I love the XServe. Been using one for over three years, two FCP stations accessing it. It's great. There are cheaper solutions out there, of course, but if that's not the most important thing, the XServe is very reliable.
A word of caution on the fibre card: There was one we had (can't remember the manufacturer) that broke -- the input socket's housing was not designed for switching out the fibre cable. The lesson is, configure your system and leave it that way.
Matt