Thanks again everyone. I think my decision is to stay with 7.
 
However, can someone clarify for me?
 
Let’s say I do a full system drive backup (clone) to another drive and in the future my system hard drive fails. Would I be able to boot from that backup drive and not have to reauthorize SPLAT? i.e. would it just open up as normal with all my plugins etc intact?
 
(I’ve never had a system drive fail, so have never booted from a backup and am a bit worried that, yes all the programmes return but they need to be reauthorized, including SPLAT)

If its an "exact copy" - either a clone or full disc image (either will work) everything should work without an reauthorization.  I just did something similar on my DAW desktop, except I upgraded to a larger drive.  Did a clone and booted with new drive and everything worked (I then expanded the "C" partition to the full size of the new drive).   However, I've done clones in the past that didn't work properly so if you do a clone, install and test it out (boot with it) to make sure all is OK before putting it away for backup.

This is why I just bought a new SSD drive for my C drive at this point in time. 
I'm not a fan of cloning because I feel after 3 years a system needs a fresh start. 
Nice clean install, no phantoms or ghosts. Everything up to date and I reverted to W8.1 just to rule out the W10 update issues for the future. 
I put the old C drive in a $12 Drive encloser so there is my back up if needed. I figure it has a pretty long shelf life. 
Sure a clean install takes a little longer but I feel it's time well spent. 
I set my laptop up beside the machine I'm re doing and will work on stuff while software loads. 
With an new SSD C drive and all my software backed up on another SSD Data drive things go pretty fast. 
 
Then later on if I find something I forgot to install, it's all there in the Data drive so takes a minute to install. I just installed 8.5 yesterday because I needed Lexicon and LP 64 Multiband. Did a bare bones , took about 3 minutes. Re scan plug ins, bingo,, done. 

Windows 8.1 gets 3 more years of Extended Support compared with Win7 although only on older hardware.
https://support.microsoft...s-lifecycle-fact-sheet

Thanks again everyone. Tomorrow’s job is to do some cloning and make sure that everything is as future proof as it can be.
 
This forum will be sadly missed if / when it disappears. I don’t post often, but have been with Cakewalk for over twenty years and often pop into the forum to catch up and if I’m looking for a solution to something. I am dismayed at the state of affairs.
 
Someone buy Cakewalk pleeeeeeease!

Any aversion towards win10 at this moment in time is missguided in regards to Sonar. I am running Win10 with the latest updates and patches and the latest version of Sonar and there are no problems what so ever. Win10 is a better OS than win 7 and Win 8.x. 
 
Then again you don't need the "best" OS version to run your DAW. If I were you though, I would update my software as much as I could before locking it in due to the developments with Sonar, or lack thereof, going forward. 
 
For what its worth I have worked in IT for 15 years and win10 in the best of to come out of MS yet. You are better off installing it than remaining with win7. Then again it it aint broke I guess ... as long as you are able to produce the OS doesn't matter that much.