Danger of uncoordinated mgmt team?

It's unclear from your post whether those 40 directs are split up between the four of you, or if you "share" management responsibility for the 40 between you (as might be the case in a plant or restaurant, where the four managers are "shift managers" and the directs are casual or out-of-sync rostered).

If the former, that's simple: you roll out the trinity with the people you manage.  You don't need to tell your peer managers anything.  If they want to roll it out with their teams once they see how much better you're doing, then help them out.

If the latter, it's a bit trickier, because trying to do O3s with 40 people is never going to end spectacularly well, and you're likely to see more questions from "your" directs about what you're doing going to your peer managers.  In that case, you'll want to at least give your peer managers a heads-up, and maybe try to get them on board (it depends on how much influence you've got with them as to how well that'll work).

Either way, though, you should *definitely* try to embody the *intent* of the O3 -- build relationships.  If you can't do a weekly one-on-one with everyone, at least try to talk to everyone about things that interest *them* as often as is practical.  The "how to do one-on-ones with shiftworkers" podcast (http://www.manager-tools.com/2012/06/how-do-one-ones-with-shift-workers) might give you some pointers if that's the sort of environment you're in.

Sounds like you're definitely taking things in the right direction.  Keep building the relationships with your directs (and your peers, and your higher-ups), move on to feedback, get outstanding results and retention, and you'll be doing things by 30 that many people never achieve in their entire career.

Best of luck,

Matt