Have started plugging humanclick into some of our sites. Excellent, excellent tool. Although it may be a bit early to tell, it does seem that it is having a positive effect on us converting lookers to bookers.
Why are more people not using it? Brett, I know that you mentioned to stay away from Java but thus far there does not seem to be any negative effect.
That is part of the problem with java/jscript and other browser side technologies, is it is difficult to gauge the impact. If you have good click-per-user data, then keep and eye on it and see if it goes down. Using to much jscript/java isn't near the difficulty it used to be, but it will cost you a few percent of your users.