Interesting idea!

Besides the space problem Jo already mentioned, I could imagine that
another drawback potentially might be a too strong focus on things
that are closely related to the burn chart, at the expense of more
subtle, but important topics.

Anyway, in my experience it's best to vary the format over time,
anyway. Pay close attention to the feedback you get at the end of the
retrospectives, and use that to decide how often to use this format,
I'd suggest.

Thanks for sharing this idea!

Cheers, Ilja