I currently have clients on Lync who utilize Open/Dynamic federation extensively. They honestly don't know how many organizations they're users are federated with (although they could check, let's be honest).
Reading the documentation, I can't see anywhere that XMPP or SIP open federation is possible with IM&P. I was hoping for them to call out that some sort of wildcard entries could be used, but I can't see it anywhere. We are trying to provide equivalent functionality for a migration from Lync, we just don't see how.
Anyone have any experience with this? In the meantime, we are just going to lab and give it a try.