@jmantze -
I have a couple of the stylus r us, and I can't tell you what the tip is made of. But, look at the thread Targus vs Roger iWand, and in the first post are some macro pictures of the tips of the Targus, and the stylus r us.
It is some type of material, but is very thick, does not look or feel like felt. Also, it seems like it will be very durable in "refreshing" (if you tamp down the fibers, you get some dead spots, as it needs the fibers to lightly touch the screen -sometimes counterintuitive if something is not catching.
Jack is an extremely enthusiatic owner. My dealings with him have been prompt, friendly, and enthusiastic. He readily admits his stylus will not fulfill everyone's expectation, but he offers a 30 day money back guarantee. He only asks that you try and learn to use the stylus properly. It requires a very light touch, and most people are used to tapping, with some force. On his stylus, this tamps down the fibers, and actually makes the stylus work worse. With a light touch, it works flawlessly. I feel it to be very accurate (for instance, I can touch the page numbers to change pages on forums like this one, without resizing the screen). I also find the light touch to be much less fatuiging, and much quicker than the Boxwave (which I think is a very good stylus).
I never asked about the material, as I figure it is proprietary. Just like I would not ask Pogo what their material is, or boxwave etc... We all sort of draw our conclusions that it is foam, or rubber, or plastic, or whatever, but none of us really know. He is applying for patent, so I fully understand why he would not want to disclose what he is using.
I think that you will find people like me - that love his styli, and think they work better than others, but I am sure you will find others that won't have been happy.
I am sort of frustrated that any of us have to worry about what sort of stylus we have to use in the first place. With the resistive screens of old ie the palm pilots -all you needed what something hard and wouldn't scratch the screen... so any old piece of plastic was pretty much alike -the only difference was what they looked like, or how big or small they were..
Good luck in your search.