Apologies not very familiar with V5 most laptops are managed in EPO with EE 6.1.1, just some legacy stuff running v4
Is it possible to upgrade individual laptops to V5 rather than big bang approach, some of these are high profile which is why it hasn't been tackled up to now, what would be the best way to test the process ?
you'd have to upgrade your entire back end, then you can upgrade machine by machine I guess - unfortunately v4 support ended some months ago, so there's not much help I can give you.
you might be able to get it from professional services - I know it's been scrubbed from all mainstream outlets many months ago now. Best to talk to your Platinum support team lead, or your McAfee partner about whether it's possible to get a copy.
Probably less time consuming (including decryption and encryption) and less prone to errors would be get rid of SafeBoot 4 and install EEPC 6 than updating all version by version.
I'd agree - if you only have a few machines on 4, I would wait until you naturally rebuild them and just deploy v6 to them then. If v4 has been good enough for the last 7 years or so, just let it fade out on its own ;-)
Just don't go deploying any new instances of v4!