I really think you will like the size of the 8.9. It just feels right in the hands for a tablet. I switched from the 10.1 to the 8.9 for that main reason alone. The screen is plenty big for web surfing and reading. I have a Kindle 3G Keyboard that is my main "book" reader, but ever since I got my tablet, I have yet to open my print subscription of Sports Illustrated. It is so much nicer on a tablet and I can read every page perfectly.
I don't know about the ASUS that much, I didn't consider it when I did my tablet shopping, I was looking at the Galaxy Tabs and iPad2. My ultimate decision was based on having one platform to rule the all so to speak. I am a PC user and have a Thunderbolt phone. I use gmail daily, as well as docs, so it just made sense for me to go with the android based tablet. Yeah, there are probably a few apps that I would like to have that are apple exclusive, but I don't feel like I am missing anything at all. Netflix works great, Google Currents is a beautiful news reader, games like Need for Speed look amazing, and magazines are amazing.
I think you would be real happy with the 8.9. Most places will have a 14 day return policy, and you should know after a day or two of solid use if you like it or not. Again, and this is my opinon, but I think the 8.9 is the perfect size for any tablet.