I wouldn't bother with a dual-boot (not necessary).
 
First, make sure you have a backup of the existing OS install (just to be 100% safe).
Once you've got that backup image file, I'd install Win10.
Win10 isn't a dramatic change from Win8.1.  
Think of it as an optimized version (Win8.5 if you will).
 
Microsoft is trying to get Win7 and Win8 users on a single platform (Windows 10).
GUI wise, Win10 is sort of a hybrid of Win7 and Win8.
Performance wise, I find Win10 to be "equal to slightly better" than Win8.

3 days ago I upgraded my Win 8.1 main DAW for my recording studio to Win 10. This time I didn't use the install DVD that I made. I just let Win Update do it within Win 8 and it was far easier and faster than when I used the DVD to upgrade Win 7 to Win 10. It only took a few hours. It first downloaded the files and then did the install.
 
Once it was done I made an image file right away. I so far found a few
things that needed some attention. I had to reinstall LoopBe1 a virtual midi
cable and Win 10 initialized the buffer and latency settings for my AVB audio interface.

There was a  1 second delay in latency when I hit a piano key and heard the sound. That was very easy to change back (only 2 parameters). All the other settings were left unchanged.
 
Later I noticed after I made 2 image files that they were quite a bit
larger than Win 8.1. I then found this folder on my C drive called Windows.old. It was huge – 17 gigs. I figured it was my old WIN 8.1 folder.

 I did a Google search and quickly found out what it was and how to delete it safely. Of course if I wanted to use the recovery feature and revert back to Win 8, I’d need that folder, but since I’ve made an image file with that folder, I could always revert back to that image  
 
But I’d prefer to revert to an old Win 8 image instead of using the
recovery feature anyway, so I was glad to delete it. After I did and did a
couple more tweaks and made  anew image file, it was the same size as my Win 8 image, which was good news for me, since I like to keep my C drive lean, so the image files are small.
 
I had a heck of a time getting my Vice Versa network backup to work with
Win 10 and my other 2 computers and found out that it was likely because of that huge Windows.old folder that had a huge number of small files that overloaded my backup program. Once I deleted it, the backup worked fine.
 
It turns out the Acronis 2015 does work fine with Win 10, yet with my Win 7
computer, Acronis 2011 was not compatible with Win 10 and I’m now using Macrium Reflect for image feels and it works great and it’s free.
 
So the bottom line is that the Win 10 upgrade for both computers has worked fine, easier than I expected and if I ever need to dual boot to the old OS to check something, it’ll be easy. I encourage all to upgrade to Win 10, after making an image file or having a 2nd HD with the old OS on it as a precaution.

Win 10 has been easy to adapt to, there’s not a whole lot of difference between it and Win 7 and 8 as far as understanding how to get around and do basic stuff. it feels good to have the latest OS for sure.

Eventually we will have to go with the "man" wants and upgrade.  With new hardware platforms you may not get the benefit using 7 or 8. So far I've had legacy devices working with 10.