I can think of a few things to think about. First, if you have ACLs in place to limit telnet/ssh and snmp access, you'll need to update those ACLs with the new IP address of your Orion server. Also, I think the Orion licensing keys off the hostname but I don't know if it looks at the IP address of the server as well. You might give SolarWinds a quick call to verify changing the IP address won't impact your license. Although the server name probably won't change, the IP address change will probably make the server look like a new poller to the database. You might have to go through the steps to reassign all the nodes to the "new" poller. You can look through the Orion migration guide to see how to do that: http://www.solarwinds.com/support/Orion/docs/OrionServerMigration.pdf
If someone else knows of any gotchas, feel free to chime in. I haven't moved servers in several years, so I'm probably forgetting something!
Hope this helps!