I for one had no idea that internal hubs with so many overdrive gears existed before I saw this thread. Sounds like a cool piece of technology to have on a small wheeled bike.
Oh, it is. I have logged about 18,000 miles on three of these (well, two were the earlier version) over the last five years.
I put an XRF5w on my Dahon Boardwalk and it seems to run pretty quiet in all gears. It also has plenty of range for my needs.
The XRF5w is definitely nice and, I agree, quieter. I assume it makes for a very efficient transmission. But there's something special about the XRF8, because its closely spaced gears allow you to restrict your pedaling cadence to a very narrow range, which makes for more efficient pedaling. I like them both.