Ok, I have to admit I'm confused now. At the moment, perf monitor seems to be working. I'm not exactly sure what change I made that made it work. Here's a summary of what I changed, mainly based on your previous reply:
I changed trusted.hosts back to '*'. I added the OpsMgr host to the NetApp's hosts.equiv file. I also went back into the NetApp Management Console and went to the Hosts Setup page and reloaded the host with "HTTPS Ok" enabled and hosts.equiv disabled. I found that if I told it to use hosts.equiv, it would fail the credential check and the XML error reported above would happen. Didn't seem to matter if I added the OpsMgr host to the hosts.equiv file or not.
At the moment, it seems like it's working. I'm going to have to learn a LOT more about this to get a better idea of why, though.