In Age of Sigmar at least, having a Saurus Musician allows you to march instead of running or charging, doubling your move characteristic instead. It’s basically a guaranteed extra 5” run, and since as @CitizenCake said the model is treated as having normal weapons otherwise anyway, it’s definitely worth taking - same with the standard bearer.I thought having musician models in a unit allows a better modifier or a reroll in some situations? (I forget what...)