Swype is extremely resource-intensive-- too much for older phones (such as my MyTouch 3G). If 8pen is less of a hog, and it seems like it probably would be, since it doesn't have to guess at what you wanted to type, it will be a great addition to the alternative input landscape.
My eris works great with its default settings...until I run a music player while trying to type. It would be great if they could dynamically scale the accuracy or something to keep response time up.
