A person who has the exact setup as me told me he did it that way:
[25/10, 11:25] We are on 3.1, although we did upgrade one at a time as and when each version came out
[25/10, 11:26] But 3.1 is fully compatible with our set up
[25/10, 11:29] Each upgrade takes 10 minutes, plus around 20 minutes for everything to boot up and the light switches to start working again