What are some of the advantages/disadvantages of using LVPECL vs. LVDS outputs?

LVPECL has the advantage of swing amplitude over LVDS (800mV versus 350mV). This produces a higher effective slew rate at a receiver and can result in lower jitter. LVPECL also offers higher clock rate than LVDS (AD9510/11/12: 1.2 GHz LVPECL versus 800 MHz LVDS).

LVDS offers the advantages of lower power dissipation and simpler termination versus LVPECL. Both have the advantage of being fully differential.