Here's my writeup on the product. I think it's pretty cool...
http://www.cbr600rr.com/forum/index.php?page=66
That's an Awsome piece!!
I got the HRC one for my bike and it works well. I did not even know about the yo yo one. I probably would have gotten it just for the ability to choose how fast you want the throttle.
Have the Yoyo on my R1 and I love it. I used the largest wheel so it's about 1/7th of a turn. I was having problems getting to full throtle even with the quarter turn that came on the bike. It definitely keeps you from loosing focus :)