Here is my situation, hopefully someone can advise:
I upgraded Win 7 32 bit to Win 10 Home 32 bit with no problems, been running it for a while. Now I want to do a clean install. However, my hardware supports 64 bit, so I hope to upgrade to Win 10 Home 64 bit, and from what I have read elsewhere that should be fine, it is allowed within the upgrade activation schema.
However, a friend just had me help with his machine doing something similar, and it ran into problems. We were using a USB with the GPT architecture for the install. During the upgrade it would not allow him to install to the primary partition, because it was MBR and not GPT. This is after we had already deleted the primary drive. We had to go into the command line and convert it to GPT from there, and then it would allow the install. My guess is that this is because his drive was partitioned, and we had only deleted one of them, as he was hoping to save the data on the other one.... It is possible if we had deleted both partitions it would have allowed us to install and done the conversion for us, as you suggest it does.... Doing it through the command prompt erased all partition data anyway and formatted the whole thing, but we didn't know that would happen when it started. In any case, when Win 10 was installed and up and running, it would not activate. It kept saying an invalid license number, or something like. (The previous version of Windows 10 had been activated). At that point my friend said not to worry, and he took the laptop and used alternative, probably less than legal methods to get it activated and running again. That is not something I have any interest in doing! It may or may not be important to know that he had never signed in to Windows 10 with a Microsoft account, only with a local account.
So, now I am about to attempt the same thing. I will be using a Win 10 Home 64 bit USB, made from the ISO downloaded from the Windows Media Creator and mounted on a USB using Rufus. (Obviously I have the option of if I want the install media to be UEFI-GPT or not). I have signed in to my current build of Windows 10 Home 32 bit with a Microsoft account instead of just a local account. I only have a single partition on my hard drive, and it is MBR and my system is a Legacy/BIOS boot, but I am pretty confident that it supports EUFI as well.
Since the current setup is Legacy I can use Rufus to create an MBR partition for BIOS or EUFI that uses Fat32, and my laptop *should* boot from that, and work...
Obviously there are benefits to converting to EUFI, though they aren't exorbitant. Is there any reason to believe that switching to EUFI and GPT will, like happened with my friend, make it impossible to activate my clean install? Would there be any benefit to using the method you published, Brink, about doing a clean install without doing an upgrade first?
I know Windows 10 prefers a EUFI environment, so it seems like a good idea to switch to that, if for no other reason than that one... But I don't have any install media that will allow me to reinstall Windows 7 to start the upgrade process over again, should everything go belly up and not activate.
Also, as a secondary question: My other machine is currently running Windows 10 Home 64 bit (having upgraded from 8.1). Would it be possible for me to make an ISO of the Windows updates from this machine and then use that to install them on the new one, once I have completed the fresh install? I am currently living in India where the internet is not only limited but even my monthly high speed allotment is not exactly high speed. If I can use these already downloaded updates that would be incredible, saving a lot of time and resources. However I don't know if it would work or not, since they come from a different machine with a different activation.
And lastly, if there is a method for successfully accomplishing that sort of update: During the installation process it downloads quite a few updates and takes a long time. Could I turn my wifi off for the first phase of the process, and once Windows 10 has been mostly installed I turn it back on to allow me to sign in to my Microsoft account and activate the install, at which point using the ISO to do all of the updates instead of re-downloading them?