Nice job! Just printed a set of these in ABS. I can confirm that these are quieter than Hofftari's dampers (http://www.thingiverse.com/thing:1707045). Might have to play around a bit with the tension on the bands to keep the printer from dancing too much though.
I'm thinking that lacing flex filament back and forth might make the stiffness easier to dial in and might not look as bad as the rubber bands presently do. A ninjaflex "hammock" might also be in order. Thanks for sharing this - it's great!