The center of the top rack was about 15 degrees hotter than the center of the bottom rack with just one plate. With no plates at all the difference was 30 -50 degrees. With both plates attached I have the same temp, within five degrees, the full length of both racks. I thought the left side of the bottom rack would be the hottest but I suppose the heat radiating from the top of the firebox portion of my baffle plate is keeping it even.
No colour change but I've only burned eight or ten times. I could steam the racks off and keep track of colour, will post results.
This seems to be the same problem I'm having......id be interested in an update to see if this has been a viable solution to even heating top to bottom.
Watching this also... This would be awesome to have and for it be removeable. I found instances where a difference in temp between bottom and top are actually helpful.
Have cooked a few times since this mod. Once the fire stabilizes the temps on the top and bottom racks are pretty much the same. I'd call it a success.
Having the lower part of the baffle removable may be handy if I wanted different temps top to bottom.