Despite the name, T9 Predictive Text doesn't mean offering word-completion.

From
http://en.wikipedia.org/wiki/T9_(predictive_text)
The word displayed on the screen is not valid until the whole text is typed.

I assume that the suggestion of using it on the IT would be to have fewer keys, allowing for a square of thumb-sized buttons.

Having a more square keyboard might allow a better screen layout, our current choices are either a full-width but very short view of the app, or only a view of the text being edited.

Having a keyboard at one side of the screen would result in a more usable proportioned area for the application (although I suspect that neither the apps nor the OS would support a popup keyboard at one side).

I still find the MessagEase keyboard to be worthwhile, although hard to learn at first (despite the pic on the site, it doesn't appear to run on the 800).

http://www.exideas.com/ME/index.html