We have 30 - 50 LPARs.
All Service Packs are copied & patched manually.
At the moment no NIM & SUMA server yet.
Question is, is IBM endpoint manager utilizing the underlying SUMA and NIM functions to download and install patches?
IBM endpoint manager uses NIM so you'll need a NIM server as well.
The IBM endpoint manager documentation includes building the NIM server.
You'll want a NIM server anyway for an estate like that, you might even want two depending on how many physical systems you have.
They can be built on a small LPAR or often people use an old, small, dedicated system.
With 30-50 LPARs, like you said above, you should definitely have a NIM-Server anyways. NIM-Servers are not only helpful in software deployment but also for configuration management, installation of new systems, systems backup, system recovery and the like.
The big exception being a heavily firewalled environment: this is where NIM servers really suck, because they need an awful lot of ports and most firewall people are reluctant to tear so many big holes into their firewall. I remember working once in a shop where you couldn't even "ping" the default gateway. One needed to get special permission to even use ping to test the failover node on a cluster. NIM was not used there.
If you do not have such a paranoid environment (and, frankly, i do not wish anybody to undergo such a torture) i strongly suggest to set up a NIM server and make all your LPARs NIM clients. It is quite easy to do, a matter of maybe 3-4 hours, all in all, to set up the basic structures and the resources needed most.