The advantages of a secondary are obvious, especially if you plan on playing indoors, not only can you run the pistol by itself, but if your rifle malfunctions or runs empty you can easily draw your secondary and use it until you find a safe location to reload or fix your primary, plus there is alot of realism with a nice gas pistol
clearsoft pistols can be had for as low as 100$, and full metal for as low as 170-200, worth the money IMO