The biggest problem you have with taller safes is moving them when stairs are involved.
The easiest way to move a light(er) gun safe on stairs is using a stair climbing dolly. In order to use the dolly, you have to tilt the safe back. That 72" safe now becomes 82" to 85" in height.
You can still move a taller gun safe up and down stairs, but you either have to lay it over, or crib it. Either one of these methods is going to cost a lot more than simply using a dolly.
If you have a lot of items that require shelf space, the taller safe makes sense. If you have to move it up or down stairs, you'll save money with a shorter unit.