I have had alot of issues with a laptop that i clean installed Windows 7 to but it would not update. That is now in the past. I clean installed Windows 10 then Windows update found the new upgrade, Windows 10 1511 (November 2015) and when it finished upgrading i went to activation, typed in my Windows 7 key and it activated. Apparently this is why they have upgraded it to save you going through the old process. As long as you have a genuine Windows 7,8 key, its good. This information was provided by Microsoft because of my numerous calls to support...... dont forget to delete the Windows.old file after the upgrade.
I think you should read all of the thread in your link.
my Retail EULA does not permit legal install on more than one pc at a time. I do not have a 3pc Family Pack licence click here
My Dell W7s can only be installed on Dells with a matching SLIC table, unless I use the sticker key and telephone activate.
As far as I am aware a bought OEM dvd can only be installed on one pc and it is then tied to that pc and can't be transferred installed on another different pc. It may work at first but in a matter of months it may start to show 'not genuine' when the checks are done.
As I said that is as far as I understand it, so feel free to put me right if I've got it wrong.