I had a friend that mounted a plasma onto metal studs awhile back. He had to cut a hole in the drywall, mount a wooden 2x4 in between the 2 studs for support/blocking and patch up the drywall. Only took an hour or so to do the whole thing, and another hour or so of sanding and painting. he did have to wait for coats to dry in between, to patch. Took 1 day but only 1-2 hours of actual work involved. He mounted a 46" plasma that weighed about 75 pounds. I don't know if this helps but if the actual building codes for your area are different, you may want to check a metal stud manufactures website. They usually have instructions and specifications for fastener pullout strength, etc...