Fella's;
If you can bring enough force and have enough time, any safe can be compromised. After all, we got into all the government vaults in Iraq, no? Re post #13, simply insure the safe itself, let the insurance company pay me to repair or have the unit replaced. If the unit is good enough, there may be no need to insure, and list, the contents, but do insure the safe.
I sell safes, not Residential Security Containers. We can also do vault doors, and do them in custom sizes. But, for a custom vault door that's worth a hoot, $2,000.00 is the down payment.
Oh, and if you do the concrete block with rebar & pour, I wouldn't worry too much about adding layers of gypsum wall board. Basically it's a flame barrier, not dense enough to be a real good heat sink. Adding it beyond the block, bar, and pour would be more trouble than it's worth.
900F