Would also depend on what your upstream rig was too. The LCD-2s play nice with almost anything, the LCD-3s are quite a bit more transparent of upfront gear and will scale higher. The bass is tighter and more defined, but when the upstream rig is up to par, the imaging, speed and instrumental separation are some of the biggest improvements.
I experienced this at the meet in Dallas, last weekend. Having had the the LCD-2 for about two and a half years, it was my first opportunity to listen to the LCD-3 (there were at least two people who brought them).
But having listened to both pair for quite a while, on various rigs, I decided I'll stick with my LCD-2. It's happy at the end of just about any chain (relatively speaking).