I think the supporting mass (i.e. scroll and point blocks) shouldn't dampen the sound, as long as the vibrating mass (the top and back) can still vibrate freely. Else, banjos wouldn't be so loud.
Also, subtle changes in sound chamber shape can affect tone a lot, as demonstrated by different guitar body shapes.
I wouldn't expect these changes to make a bigger difference than, say, sound hole shape, but I would expect them to make some difference.
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