Man does that look good! Maybe the piano board keys could be bigger, or less time consuming could be biggish, square, even sized blocks in similar colours to the center blocks. That would balance against the size of the strips in the center blocks.
I did that with a flying geese quilt, didn't have enough fabric left from the geese (green and gold scraps from a sale bin) for borders so just made 7"- 8" blocks then bound it in the darkest green.
Getting the blocks right was not easy as there was no common denominator in the length and width of the quilt for cutting exactly the same size blocks for the top and bottom. I had to make them a very slightly different size but it works. Will find quilt and photo it to post.