I really like your latest picture with the more random placement of the blocks (also going into the border).
One thing to think about is whether you want to have the blocks placed so that it appears that they are all being illuminated by the same light source. If, for example, the light source is in the top left corner, than the blocks would each have their lightest side on that side and their darkest side towards the lower right side. If the light source was at the center of the quilt, then each block would have its darkest side be the one closest to the border. Or you could deliberately have the blocks placed randomly without factoring in the light source. I don't have a preference among these options, but I suggest playing with each of them and seeing if one of them is more appealing to *you*. Lots of options!
Looking at the latest picture again, I'm not quite wild about the blue block being placed in the very center of the quilt, as I think it diminishes the sense of motion (like the blocks are exploding outward). I think moving it a bit away from the center would be nicer. I also really like the scattering of small dots of color you have in your very first picture, near the center of the quilt, as they also make it feel like everything is exploding very fast out of the center. Putting those back in would be my recommendation.
Very nice work - you will end up with a very fun, and very interesting quilt no matter what options you choose here.
