If you didn't use sheetrock and used Duroc (concrete board) would it be better?This is not actually a bad idea with some modifications. I worked industrial construction for almost 20 yrs. One of the most secure facilities I worked on was a SCIF (Sensitive Compartmented Information Facility ) Basically a room that was secure and protected from all forms of eavesdropping. The room was framed with 12ft heavy gauge 2x8 metal studs on 8" centers for the walls and ceiling. the studs were cross-braced between the studs. Once the electrical was run and other penetrations were done it was cover with 2 layers of some kind of composite board 1/2 thick on either side and the double 1/2" drywall. the room had a raised floor and copper mesh on all concrete walls before the inner walls were built. There is no way a sawzall would cut through that wall in any reasonable amount of time. You could accomplish similar strength with 2x6's or 2x8's on 8 in centers, double 1/2" or 3/4" plywood sheeting and double drywall. You'd be hard pressed to defeat that wall with a chain saw in a reasonable time. You could even throw some rebar in there ever few feet to slow down your average saws.
Been thinking of this for a long time now.