You might want to consider some weld hardfacing on the teeth to minimize wear over time.
I am very interested in this build as I've been considering building the same for some time now. Nice work!
I think I looked into those and for the size I needed they were getting expensive. I needed something like an 1" thick on one side and about 1.5" on the other.
I ended up buying this 4" sleeve and chopped it up in the bandsaw. Worked pretty well and was cheap too ($12).
EDIT: Whoa, I guess I got a steal on this boy. It now lists for $54