I currently doing all my editing work in Final Cut Express, what exactly does Final Cut Pro do better? I know the Apple website gives some insight, but it doesn't exactly compare the two well.
To me, Apple Color (a $10k application before Apple bought and rebranded it) alone is worth the price of admission, stepping into the Final Cut Studio realm. But everyone's needs differ.
Also, if you find yourself editing codecs like DVCPRO-HD, HDCAM, REDCODE, etc. down the line, FCP supports these codecs, whereas FCE does not.