I wouldn't use it. I saw on their website were someone asked if it was safe on a BBQ and they said it hadn't been tested and gave some generic answer about fire bricks.
You'd need some fairly high amps to distort the charcoal chute at 1/4". Cook chamber more likely. But if you work methodically and slowly, stitch welding every couple of inches and leave it to cool between every three or so welds you can minimise distortion to a large degree. It does take a lot longer but looks so much better than the rushed, overheated welds and warped cook chamber.
just my 2c worth.
Learning generally boils down to "Repetition or the avoidance of pain", some people learn by doing, some by watching and some just have to pee on the electric fence.
Whether you think that you can, or that you can't, you are usually right. Henry Ford