I have not switched, but I'm extremely tempted. I'm also thinking that we are early in the Spin Effect intro right now, so as I mention in the video review, I'm eager to see if Wilson roll this out in a racquet more to my spec.
Both Jason and Spencer are switching to the Steam 99S. They are both playing some very solid tennis with it.
I've been doing so much testing in the last few months that it is rare that I've had the chance to go out and hit with something that is not for an upcoming review. When I have had the chance to hit for fun, I've been hitting a lot of wood racquets (I'm discovering the beauty of wood strung with poly! Look for a blog on that sometime in the future). I've also been hitting a very special (to me) fully custom racquet I will also be reporting on in the future.