When adding sand to an existing tank, I would suggest using the "live" bagged sand just because it is less dusty and will cloud your tank for a shorter period of time. This, I believe, is really the only advantage of using "live" bagged sand.
No, I haven't yet, I have a teeny tiny Kole Tang in the there helping with Valonia right now, so the tank is rather full for as long as he's renting space.
