Secure HE43-2 air sealing

This model has two swing out doors with no seal inbetween them. There is also a 1" gap in each door seal. These leaks prevent one from throttleing down a fire much on these, and the burn time is less than 4 hours even with ideal wood. Is there a reason that they prevent throttling these down more? While this is an attrractive fireplace, it is not particularly efficient. Any thoughts?

Anyone else have the Security HE43-2?