Pixel shader is much more accurate for complicated combiner modes in most big titles, GE, Zelda, PD, etc. If you want to compare, here are a few examples:
Zelda logo
Mario Tennis player shadow, and shadows in many other games
GE menus
Conker, the whole game
High end combiner or 2-stage combiner (manually configurated combiner settings) are OK to run these games, but not as beatiful as pixel shader.