Font Reserve Server is an atrocity, the biggest handicap I have ever faced in ten years of pre press production. It is unreliable and unpredictable, and Extensis' "support" is a cruel joke.
My employer forces us to use this, and connect to a font server in another city. It has cut productivity by at least 20%. Every time you import a graphic, open a file, save a file, the application times out while Font Reserve goes looking for a font that is already open. The minutes of non-productivity add up quickly.
Of course, that's the best case scenario. Font Reserve frequently fails at it's basic task: automatically opening fonts.It's crash-prone, and a memory hog.
Around here, FR has some nicknames - most unprintable here. Font Reverse. Font Regret. Font Severe.
Be afraid, be very afraid.