Going back to Windows 7 from Win 10. Pros/cons?

Well for one thing, you're going to an OS that is now 8 years old, and all the security and compatability issues that entails. Mainstream support for it ended in 2015.
I have seen occasional issues with newer drivers not working in 7 - but these are rare.

I kind of agree with the first reply you received.. That being said..............I had win 10 installed for a while. Went back after a month or so.
I still run Win 8.1x64 on my daw. I did put win 10 on my laptop, just to have. Win 98.1x64 is still supported.
I know your asking about win 7, just thought you would like to know. I had 7 for a long time I like it.
But Win 8.1x64 is newer, still gets regular updates, although I only install the security updates at this time.
 
Very, very stable with Sonar Plat.
I don't need the latest and greatest. I need what works and is stable.
I am guessing you already own Win 7. 

I have left my DAW on Win7 for the reason of stability, and not had issues with it. I intend to leave it this way for the very reason of not buying into the "forced updates." Properly imaged, Win7 can be restored quickly and doesn't screw up authorizations of software (e.g., I do not need to continually reauthorize XLN stuff, etc.).
 
That said, my work computer I had updated to Win10 (18 months ago), and it began to act flaky just a few weeks ago; so I did a system restore (HP laptop), which put it back to the default Win7 shipping configuration (about the only thing I am happy for HP's bloatware). Win 7 authorized without issue which sort of surprised me since I was under the assumption that the authorization was superseded by the Win10 installation (was still in the free window when installed, so HP may have saved the day). Some Win7 updates are now "in bulk" so even though they are sequential, some are roll-ups which include several patch points versus a zillion installation files. It took roughly 4 hours to bring the machine back up online, get updates, and strip the HP crap from it.
 
After talking to one of the IT folks last year, I discovered that 5 of the security features in Win7 Ultimate were removed from Win10 (a couple via the actual Win10 updates themselves), and are only available in the Win10 Enterprise version (or Academic version, ironically). Three of those I use, so if/when I ever go to Win10 on my home machine it will be the Academic version, but I have zero intention of doing so. As stated above, Win7 is a very stable and (more importantly) static OS.
 
Win7 will officially lose "extended" support on 14 JAN 2020, so software development will continue probably to support Win7 at least until that date (i.e., new software builds).

I can't speak to Win 10.  I bought a copy but haven't used it as Win 8.1 has been rock-solid on both of my systems.
 
... So that would be my recommendation if you are leery of Win 10 or it's been problematic for you.... Go with Win 8.1.
 
Not sure why you would choose Win 7 over the obvious choice of a newer O.S.  Win 8.0, I understand, was a dog for many, but 8.1 fixed all of the issues and added many optimizations.

Thanks everyone for weighing in.
 
Here's my situation: I have a 2012 Dell XPS 8500 that came with Win 7. When free Win 10 upgrade came out, Microsoft did one of their scans and said my machine was ready to go with the update.
 
Dell, however, said the 8500 wasn't supported for the Win 10 update. I decided to go for it because it was time time buy a new computer for work anyway, and I would downstream this one to be my DAW. Plus, I could roll back to Win 7 if I needed. Well, so far (over a year), everything's been working fine in Win 10, except for the occasional PITA things MS pushes on Win 10 users (read: forced updates and its headaches).
 
However, I'm afraid to do Dell system updates (BIOS, chipset, drivers, etc.) because as far as Dell is concerned this is a unit with Win 7 on it, not Win 10, and the whole thing could end up in a nasty knot. Guess, I'd have to wipe everything and start over anyway...
I have a USB that will set everything back to factory fresh. Got it from Dell. I also believe Windows has extended support for Win 7 until 2020. https://support.microsoft.com/en-us/help/13853/windows-lifecycle-fact-sheet

In planning for a new SSD for this unit, it sounds from others as if a fresh OS install is the best, cleanest, most ideal route. I can buy a copy of Win 10 to do the fresh install onto the SSD, or I can rollback to factory fresh, Win 7, as it was in 2012 when Dell shipped it. I'd install that on the SSD, along with Sonar and related.
 
Not sure what route to take, if I do a fresh install. The other option is to use the Samsung migration tool and move everything to the new Samsung EVO 850 SSD, although as someone said earlier, then you move all your old system ghosts with it.
 
Hmmm...

Billy86, you don't need to buy another Win 10 to do a clean install.  You already "own" Win 10 and if you sign in to Win 10 with a Microsoft Account (e.g. I have a Hotmail account and use that) then you have "digital entitlement".  All you need to do is download Win 10 and create a bootable media -DVD or a USB Flash Drive.
 
You don't need any Dell drivers either, Windows is providing the latest driver versions.
 
Here is the instructions from the www.tenforums.com  Tutorials (use Option 1 Media Creation Tool).
https://www.tenforums.com/tutorials/9230-download-windows-10-iso-file.html
 

Okay, all. Like I said: Hmmm.... nothing's easy.

Billy86 I can buy a copy of Win 10 to do the fresh install onto the SSD, or I can rollback to factory fresh, Win 7, as it was in 2012 when Dell shipped it. I'd install that on the SSD, along with Sonar and related.
 
Not sure what route to take, if I do a fresh install. 

If you're prepared to purchase Windows and create a new install, why not buy Windows 8.1 instead? It's easier to deal with and configure than Win 10, newer than Win 7, and runs very nicely as a DAW OS - I'm using it for my workstation. There are reputable dealers on eBay and elsewhere who will sell you a new Win 8/8.1 product key that is affordable. And then no more Win 10 headaches.  
 

I tried putting Win10 on a Mac a few months ago. The idea being a dual-boot system so I could run a few Windows games and a few small Windows only applications.

So I downloaded the relevant Apple Boot Camp drivers for Win 10, installed it and ran Windows update. After it had finished and rebooted I found it had replaced some of the Apple drivers, including the video one, with generic Windows drivers.

So off came Win10 and on went Win7. End of problems.