The mu-metals look quite nice, and a more than adequate solution to our problem (and a few others we were having) for the time being. I don't know what kind of current we'll use down the road, but since we do have a DC set up going right now (a transformer charging into a bank of pretty hefty...
We're trying to create what amounts to an electromagnetic jack, having a series of rotating, electromagnets in a bowl shape, with some sort of potentometer or rheostat to control ascent, and a semisphereical piece of ceramic with an inch-thick aluminium plate over the flat part and neodynium...
My roommate and I are working on a backyard physics/engineering project, with the intent to hopefully scale it up to massive proportions. One of the issues we recently came across, though, was the matter of focusing our electromagnets for both efficiency and to keep from effecting anything else...