My extremely humble little studio is running ok right now on Sonar Studio X3 /  Windows 7 x  64.  I have one week left on the option to upgrade to Windows 10 for free. This would require, according to what I've seen at the Cakewalk site, an upgrade to, say, Sonar Professional for $99. (Platinum is $299..., a bit much). It's my understanding that my Ozone 7, and Waves plugins will work on Windows 10, no issues. 
Since Windows 7 will receive extended support till 2020, do I have anything to worry about?  Just stand pat and carry on?  But...  Perhaps it would be nice to get the added features of Sonar Professional...  not sure.  Time for an upgrade anyways?
One other thing...    can anyone recommend a competitive DAW they like better than Sonar for around the same price? 
The one big major concern here is that my current audio projects need to still work on the new DAW, whatever it is. 

I avoided the Win 10 upgrade for the simple reason that everything was working fine.  A couple weeks ago, I turned on my computer and got the message, "welcome to Windows 10!"  I have no idea how Windows was able to do this without my permission.  I am assuming that I somehow inadvertently did something that granted the permission.
 
The good news is:  everything seems to be working just fine.  No problems so far.

Gary McCoy
I avoided the Win 10 upgrade for the simple reason that everything was working fine.  A couple weeks ago, I turned on my computer and got the message, "welcome to Windows 10!"  I have no idea how Windows was able to do this without my permission.  I am assuming that I somehow inadvertently did something that granted the permission.
 
The good news is:  everything seems to be working just fine.  No problems so far.

Cool.  What version of Sonar are you running ?  X3 apparently has not been approved by cakewalk to work in Windows 10. 

1) You do NOT have to upgrade Sonar X3 to move to Windows 10.  It runs just fine. 
 
2) You WILL likely have to update your audio interface drivers to a newer version that IS compatible with Windows 10.  Go to the web site for the audio interface manufacturer, and check their driver support page(s) to see if they indeed have created drivers for your exact model of audio interface for Windows 10.  If they have not done this, then you will need to consider either remaining on Windows 7, 8.0, or 8.1, OR purchasing a new audio interface where the manufacturer HAS created drivers for running on Windows 10.
 
3) Your 64-bit plugins will most likely run on Windows 10, and I have not myself seen any reports of any of the more popular ones failing to run on Windows 10.  I don't know anything whatsoever as to whether or not 32-bit 3rd-party plugins run in a 64-bit Windows 10 environment.  I, and many others, have either completely or nearly completely moved to running 64-bit plugins altogether, as bridging 32-bit plugins has caused so many folks so many problems that most seem to have completed the move to 64-bit plugins, with perhaps a handful that seem to run OK when bridged to a 64-bit Sonar.
 
I will be converting my primary DAW from Windows 8.1 to Windows 10 sometime early next week, as an upgrade in place.  I will be creating a disc image of my C: drive prior to that, in case things go South.  the only things that live on that drive are Windows, my applications, and associated AppData and ProgramData.  All user libraries and things like Cakewalk Content, Projects, and sample libraries live on separate hard drives 'Data Drives', so those are unaffected by my upgrading to Windows 10.  
 
Should an upgrade in place fail to run smoothly, I will have completed enough of the process to where Microsoft will have the requisite authorization key registered in their system, and I will then likely combine doing a clean install of Windows 10 with my upgrading my motherboard to something more robust than what I currently have.
 
Just do your homework, and have a plan for both completing an upgrade, and for recovering from one if it fails, as well as being prepared to have to do a clean install of Windows 10 and all applications, should the upgrade in place not work properly.  With proper backups and plans for installation and recovery, you should have all bases covered, provided you made sure there are indeed device drivers available for whatever audio interface you plan to use with Windows 10.
 
Bob Bone
 

They want you to upgrade, can you blame them,, Cakewalk and Microsoft are sort of using a heavy hand with this upgrade business. Bet you they extend the offers too... If X3 and W7 is working and there is nothing on the list of new features that turns your crank I myself would just stay put.. I personally don't care a rat's arse which OS is running in the background because I don't really use it.. I just turn the computer on and go straight to Sonar or Wave Lab. 
I'm typing this on a laptop running Windows XP. I put an SSD drive in it and it runs like a top. 
My laptop DAW runs on W7 64 bit and it runs better than a brand new Lenovo we have at work that is bloated with W10. 
My office computer is now W10 which I took the bait and did myself,, but,,  like Gary above I turned on my smoothly running W8.1 DAW desktop one day only to find the same "Welcome to windows 10"  message? Serves me right for forgeting to disable the internet after I updated Sonar. PITA to re authorize a few apps like AD and Stienbergs iLock. But I see absolutly no differance ,, it was a boring upgrade. My desktop and everything looks the same as it did in W8.1. 
I think what happened is you get so used to the W1o upgrade nag screen and you just blindly close it.. Mircosoft figured this out and I think they moved the buttons around so you were actually saying OK go for it. 
 

My DAW is still on Win 7 and will remain that way until an upgrade becomes 100% necessary to run Sonar, which hopefully won't be for a while yet.
 
There are no Win 10 drivers for my interface so I have to also figure in the cost of upgrading that particular unit.

I run Sonar X2 Producer on W7 x64 which works fine. I also cloned that SSD to another SSD. Then I upgraded W7 to W10. As I read somewhere above. You need to be sure that the equipment you use like audio interfaces have W10 drivers available. In my case it is and X2 runs fine on W10, even X1 does.
Later I decided to upgrade to Sonar Platinum Life updates and that runs fine as well on W10.
 
Jan

I put off upgrading my Windows 7 machine until last week.
 
I did the "in place" update and everything is working fine.  I haven't even got round to updating my interface drivers - it all seems to be ticking along nicely.  All completely painless.
 
Not sure I am a big fan of 10 - guess will just take a bit of getting used to.
 
I was perfectly happy on 7, but feared that Sonar would stop working on it eventually.  Not much point having Lifetime Upgrades if Sonar won't run on the OS. 

Chevy,
 
If it ain't broke, don't fix it.
 

There are claims of improved performance,, not sure why or where and I probably wouldn't benefit because I still use the same features I used in Sonar 8.5 ...For me the best reason to upgrade is the better quality VST's and plug ins. Still not 100% happy with the editing features now but you slowly win the uphill battle and work gets done. 
 
Overall the best reason to keep abreast and fully updated is the support and functionality. You fall behind and your on your own. 
My gripe with upgrading is it takes time away from recording to muck about and then re learn how to do something. I feel like I could never fully grasp Sonar right now. 
I'm not going to do the lifetime upgrade because right now I don't have the cash. I had to upgrade my PA system and I'm still paying that off. My hobby has to break even ( wife rule#4)  so gigs and recording clients pay the way. Sonar is very stable right now and I'm only interested in if they ever add full wave editing like Wave Lab. If there's any bugs lurking I've yet to find them.