Brick,

It's not a fuel consumption issue. I actually expect to use
marginally more fuel (initially, till the bricks warm up.) What I am
trying to do is limit temperature swings when opening the cook chamber
to mop, or tending the fire. If I open the firebox door to tend the
fire, the temp drops about 25 to 40 degrees, and takes about 15 minutes
to recover. The hot bricks will give up heat when the door is open to
minimize the size and time duration of the temp swings. It's a cheap
thing to do that may improve performance, if only marginally. If I
ever did want to grill I can always pull the bricks out first. Thanks
to all who replied.

Regards,
Scott