Yes listen to Ronin. People tend not to realise how important the roof structure is to a car. This is why a pop-top is never as stiff as the same car in hardtop fashison. Heck even a sunroof model car usually is less stiff (nevermind buttload heavier in the wrong place).
Also on a savlaged title car, how does insurance value the car then? Would you not have to be forced to a fixed value insurance which would make insurancing the "salvaged" car more expensive on a car that has no resale value. That really sounds like it can become a BIG money sink quickly.