I had not taken up the free offer of Windows 10 upgrade as:-

i) Win 7 did what I needed.
ii) was concerned I'd lose ability to move my license to new hardware (I have Win 7 Pro retail).
iii) privacy concerns.

So what changed my mind?

Firstly I thought there's slightly more than ~3yrs support left on updates for Win 7 which will mean by that time I may want another OS and if it is going to be Win 10 I'd be paying. Secondly as DX12 is not available on Win 7 I may miss out on some performance boost in games that have it. Thirdly after reading some information in this thread under heading What happens if I change my motherboard? it seems I would have retail rights as I had retail Win 7.

On the privacy aspect it seems if I take the time to install Win 10 as per some guides and then do other measures I can curb it and then I also thought is it as big an issue for me? well no.

So downloaded Windows 10 Anniversary ISO using the media creation tool, burned on DVD, disconnected all other storage devices within rig, connected a blank spare HDD and installed it with my Windows 7 Pro key on the 04/08/16. Couple of days later using the information in this thread I verified I have retail Windows 10 Pro (my screenshot).

Anyone else upgrade after the deadline?