Administration rights is not logical if you DOS boot into ram and do whatever you want to with drives and load any OS you want.
I believe you are confused over MS's inherent Money Grabbing Upgrade Policy.
If you require Administration Rights to get that file - By all means do it - I never had the need.
With any Upgrade of Windows you loose System Prep.
My concern of this MS Win7 and 8 Upgrade to Win10 - If you elect to do a fresh install - Do you have the SYS-Prep option - That is you can load a Win10 Sys-Prep image onto any hardware you have and keep it Authentic.
In other words, with an Upgrade or SP, you loose SYS-Prep and are trapped were you can't migrate your Windows OS image to a different hardware platform without paying MS for authentication.
Does a Win 10 upgrade version with a fresh install include SYS-Prep with Authentication like Win7 and Win8?
Are we talking about "retail box" or OEM? We all know, and have experienced the problem where a motherboard goes on the fritz and needs to be replaced. With OEM, you make the phone-call and get a new activation key. At this point, I can't guarantee it, but I don't see how M$ would change that policy even with the phone-call hurdle because you activated a Win10 install with the Win7 product key. It wouldn't make sense for them to change that policy. Motherboards go on the fritz all the time, and probably as much or more than people trying to get extra mileage out of an OEM install and product key on all new hardware.
Whether you choose to use SYSPREP in a reinstallation wouldn't matter if you still have to go through the telephone hurdle for a hardware change. If there's no hardware change involving the motherboard, you'd simply reactivate with the product key.
The reason I made separate installation of Win10 on a different boot-volume and in dual-boot with Win 7: I want to feel comfortable with Win10 before I burn the bridges behind me. But I'm also assured that, once activated in that sort of situation or in the more typical "upgrade" scenario, you could simply do a bare-metal reinstallation of Win 10 without dual-boot including Win 7, and your Win7 product key would activate it without difficulty.