I agree with Don S. Lead is toxic. I would not use it either. I just filled the Elac stands for the NX-Studio Montors that I just build with play sand yesterday. Plenty dense and inert stands now.
The most important thing you are trying to accomplish is to stop the ringing of hollow metal column's. Any fill like sand, cat litter, crushed walnut shells, rice etc. will work.
You won't likely get agreement on which sounds better, like anything else in this hobby.