[0] Although, I would argue, in cases where no alternative exists, if the FBI policies prevent NAND mirroring, they should be revisited. Even if it has the potential to be destructive, they would only be destroying otherwise unusable information.

Eh? no, destructive methods are a big no-no, this isn't a dichotomy.

The information ins't unusable, they can try force apple to unlock the phone, or wait until some one else comes that can do it without using a destructive method.

You can't destroy evidence because you can't do anything with it at the given time.