As elaborated here already, things do differ a lot when comparing use cases. Out of my personal experience / view, i would dare to say:
- On the Gateway, CPUSE is well enough for installation - as long as you have sufficient disk space and partitions left, as the previous version will remain in a separate partition so you can revert back to it (see the discussion here: How to advance Upgrade Smart-1 210 SMS r77.30 to 80.20). On the other hand, if the GAiA configuration is rather simple, a fresh install, FTW and policy install is a quick way to a clean GW with much free space (remember situations of spontaneous local logging ?).
- One criteria i find very important is the age of the installation on the specific hardware and the detailed installation history. Although the residues of older versions on SMS are much smaller nowadays (😉), i prefer SMS Advanced Upgrade especially for major version changes. New FS can also be an argument here in larger scale environments.
- with VMs we do not need to ask such questions 😊
- with VSX we often do not dare to ask such questions 😕
- with StandAlone deployment we just did get only the short end of the stick 😞
CCSE CCTE CCSM SMB Specialist