What will Orion do if a switch ever re-indexes its interfaces? Will the next rediscovery interval fix the problem, or will I have to manually re-add the nodes?
Orion will automatically handle the reindexing with each rediscovery.
If you're worried, use the snmp-server ifindex persistent command on Cisco IOS - although the previous post is correct in that solarwinds will just figure it out on its own.
I've rebooted devices after removing linecards, changing the ifIndex of all of the interfaces. Solarwinds always seems to sort it out.