Update: I did the clean install procedure after the initial Win10 update as outlined at The Verge, and all was groovy. 32-bit to 64-bit without issue and all of the remnants from the Win7 install are no longer an issue. I had a little trepidation about the activation after wiping everything, but whatever madness MS does around hardware imprinting and licensing seems to have worked flawlessly.
Update: I did the clean install procedure after the initial Win10 update as outlined at The Verge, and all was groovy. 32-bit to 64-bit without issue and all of the remnants from the Win7 install are no longer an issue. I had a little trepidation about the activation after wiping everything, but whatever madness MS does around hardware imprinting and licensing seems to have worked flawlessly.