While the above process is correct there is one exception that will turn it on its head. If you are using Fibre Channel storage when upgrading over that version gap you need to worry about a family of bugs that can result in storage outages during IO...
I was trying to do something similar between 2.1(1e) Domain and 2.2(5d) emulator or 2.1(1) emulator without success. Live import of a 2.2(5d) Domain to 2.2(5d) Emulator was the best I could do and like for like versions seemed to work better. Trying ...