[kgtm]

If you are worried about telemetry, like some people are, the only version that allows completely disabling it is Windows 10 Enterprise.

Having said that, the main reason for at least initiating the update is to mark your existing key as "Windows 10 eligible". After the upgrade is complete, you can easily roll back to the previous OS version (from within Windows, trivial and no side effects) and you can continue working on Windows 8.1 while now having a valid Windows 10 key for the future.

You can also perform the above procedure using a VM snapshot, upgrading, and then simply using your snapshot instead.

If you are a developer using Windows as your main OS, a very strong reason to upgrade and not roll back is the upcoming Anniversary Update. This will bring the "Windows Subsystem for Linux" which means you can natively run the entire Ubuntu userspace, like bash, tmux etc. That is pretty exiting!

IMO if you rarely use the VM in question, your top priority should be future-proofing your Windows 8 key.

[beefield]

Thanks. It is literally months since I last launched the VM, so I am not that worried about telemetry. I guess I am balancing between wasting some time now to make the upgrade vs. being pissed at myself in a few years time when I suddenly need to do something on windows 10 and need to purchase the license.