I would rather stick with Windows 8. But I am not sure if I will be missing out a lot. 

It is not necessary for SONAR, but Windows 10 is much better then Windows 8.
And at the moment you get it free.
I have updatet all my PCs and laptops.

THambrecht
It is not necessary for SONAR, but Windows 10 is much better then Windows 8.
And at the moment you get it free.

 
Will any part of Sonar not function properly in Windows 10 environment? You know how it goes when you make a change in your system and then you spend next few days tweaking to get your DAW in a good mood. 

I upgraded to windows 10 a long time ago and have had no problems whatsoever.

cowboydan
I upgraded to windows 10 a long time ago and have had no problems whatsoever.

Same here (or hear if you wish).

I held off on upgrading to Windows 10 from W7 because "if it ain't broke, don't fix it." I regret not upgrading sooner, because SONAR is really snappy with W10. I also like W10 better. 
 
You might as well upgrade. If you don't like it, you have 30 days in which you can roll back to what you were using before.

After July 29th, 2016 the upgrade will no longer be free.

Either way, you'll be fine. It works well under both Windows 8 or Windows 10.

Hmm, this thread has got me thinking. I've been humming along with 8.5, but due to stability issues I will be upgrading to Sonar Pro soon. I'm still on W7, and am determined not to upgrade to 10 because; well, I have my reasons but they're irrelevant here. My plan is to stay with W7 Pro, maybe forever. So, how long into the future will Sonar support W7? Would I have to stop updating at some point, so my version of Sonar doesn't get "ahead" of my W7? Or should I bite the bullet at least on my music computer, and get W10, continuing to use Linux for everything else? 

Standard W7 support is over. Extended support to 2019 (IIRC).
I would upgrade to W10 prior to July 2016 when the freebie ends.
The spyware phone home thing is very much overblown for W10 if that is your concern.
I upgraded W8.1 in place to W10 and had no issues whatsover. W8.1 is faster than W7. W10 is faster than W8.1.