This would definitely be helpful for me, because I'm trying to flesh out the Yoshi's Island memory maps, and literally the first entry in the YI ROM map claims it ends in the middle of an instruction.
I forgot about the contest until the Saturday before the deadline, so I ran out of time to actually code my own routine for moving the Boo Ring. Instead, I stapled on a call to the normal sprite position-updating routine. However, when I was copy-pasting the code to move each of the RAM values to where the routine expected them to be, I somehow missed moving the subpixel position over, which is what what caused the bug. (If you want more information on why it caused the exact behavior that you saw in my submission, feel free to PM me.) If you want so see what it was supposed to do, I just uploaded a fixed version to my file bin.
I also had a few more features I wanted to add but ran out of time, like changing the palette to the Big Boo palette (sprite palette 7, I believe) and making the individual Boos in the Boo Ring face Mario and hide when he faces them. Once I've implemented those, I'm planning on submitting it to the SMW Sprites section. (I probably won't implement the suggestion that the Boo Ring should stop rotating when Mario is facing it, because then you could fall into it when the large gap is at the top and be forced to jump through a small gap between Boos to escape.)