Well, I haven't tried it yet, but I must say I have to have stall horns, because:
A) This is a sim, not real life, I have no other information provided to me that the A/C will stall other than the horn.
B) In RL A/C, you have many things warning you of a stall, shaking of the stick, the aircraft frame, the motion your body makes within the seat. In a sim, you might have a shaking screen, but that will not give you enough info on how far you can push it like real life does. thus, the stall horn is very good with me. Adds about 5 other senses that I lack while flying in real aircraft.