Metal's nice if you have the skills and access to affordable metal. But it will be noisier in use, won't it? And if you line it with something like neoprene or some other sound deadening material, the costs will certainly be much more than wood products.
I've seen some projects where folks have used foil-backed butyl rubber weather sealer sheets meant as a window flashing sealer in home construction as a less expensive substitute for 'Dynamat' and other such car audiophile -dedicated material and reported very good results.
http://www.lepageproducts.com/ProductDetail.aspx?pid=150
The one serious benefit for metal would be minimal loss of storage space due to the structure of the thing. A lot of these drawer within a slider withing a box contraptions we're seeing here give up ~~30% of the storage volume to just the structure itself. That's just way out of proportion, IMAO. Well executed metal construction would take very little of the storage volume.