This quilt is going to be beautiful but I am worried that you won't really see the quilting designs at all in the busy-ness of the bargello and all the fabric. It would be a shame to do all that work and not hardly be able to see it. My experience with quilting on busy prints is the quilting just doesn't show. Your idea is divine but I think it would be better saved for a plainer fabric so the koi and dragon really show! Then again, you could back it with a solid plain fabric and they would really show from the back.
Edited to add, for hand quilting it will be difficult going through all the seams of a bargello as well. I hate to sound like I am raining on your parade or being all negative, this is just my experience.