Upgrade to Win 10 to use Sonar Platinum?

There are a whole slew of memory management, CPU scheduling and audio stack improvements from Windows 7 to 10, so the performance gains on multicore CPUs are pretty decent. Windows 10 has also been engineered to support a smaller memory footprint since it runs on tablets and phones(!) as well. All together these improvements to the OS do translate into better perceived performance. Whether or not the upgrade process is worth the potential performance gain is up to you, and that's what makes the technology merry go round so much fun. 
 
So yeah, the core OS is better, but to me there's an even more interesting world being born that you have to be on Windows 10 to live in. We all know Sonar has moved to a continuous update model, but it's important to remember that Microsoft has done so as well with Windows 10. And part of MS's strategy is to overhaul and modernize their ancient and somewhat creaky MIDI and audio stack into something more appropriate to the future.
 
Microsoft has already juiced up the performance of WDM with the intent to make it as fast as ASIO, and there's also some pretty fun new MIDI API's available that address a lot of the problems in the old framework. Those updates have already been and will continue to be delivered as part of their rolling update program. I'd be willing to bet that Cakewalk is looking at some of the new features already with an eye toward how they can use them to snazz up Sonar's performance.
 
Imho, the virtuous cycle of cascading improvement and new feature development between Microsoft and Cakewalk will only become more apparent as time goes on. Pity the poor DAW companies that must match both Microsoft's service model development cycle and Apple's more traditional version release cycle!
 
So Windows 7 will work well for you, but the future is Sonar on Windows 10. I do wish you good luck with whatever you choose to do!