If you haven't seen the Quickfire TK or Plum 87 (I think that's what it's called), they have that layout except with a 00 key, and it acts as part of the arrow keys when nun lock is off, while the keys in the third/fourth row act as the navigation cluster. An excellent layout, in my opinion.
EDIT: Looked closer, it's pretty much the exact same except everything is one row lower and the pause/stuff is on the upper row.
EDIT 2: Nice pi post!