I'm guessing it would be prudent to uninstall Sonar before upgrading the OS then re-install. Although if unnecessary that would be optimum due to limited internet resources at my studio. Any advice?
Thanks!

It should not be necessary. Worst case, you can perform a clean reinstall after upgrading the OS. The procedure is the same. Addictive Drums will need to be reauthorized. If you use the Command Center unless you are in the habit of purging the cached files, the SONAR installers are still on the PC.

Hi. I did an inplace upgrade to Win 10, without uninstalling SONAR on my laptop. Have not had any problems. I would however try to do a clean install of Win 10, if possible. I have seen other people having issues after doing an inplace upgrade.
All the best.

I had no problems going from Windows 7 64bit to Windows 10.  As someone mentioned, you will need to go to your  XLNAudio account as Addictive Drums thinks you have a new computer.  You simply add your Windows 10 computer and remove your Windows 7 computer - they make it very easy.   

Thanks a lot! Something to do this weekend...Oh boy

Good news your Presonus drivers appear to work with Windows 10.  Mine did not  because I had an old Firepod (Original version).    
Good luck this weekend.  I switched interfaces and upgraded in place Windows 7 => Windows 10 without issue and without uninstalling SPLAT.
 

Don't uninstall Sonar. It'll work just fine if you keep it - BUT - uninstall all win7/8 audio interface/hardware drivers before you upgrade. It might not be possible to uninstall properly once you have upgraded to win10 (I had one Roland driver, which I forgot to uninstall get stuck i.e. I cannot uninstall)

I did the W10 upgrade over Windows 7 last weekend and did not uninstall anything.  I was actually really surprised at how smoothly it went and how stable everything has been.  The only problem I had is that, apparently, it renamed my computer, so I had to reauthorize numerous plugins, mostly the ones that used my computer name for authorization (e.g., ToonTracks, AddictiveDrums) or some that used challenge/response (e.g., Spectrasonics).
 
Also, I use a MOTU interface with ASIO4ALL and did not uninstall it before upgrading, but it's working perfectly for me.

In place upgrade leave everything in place.  One word of caution is if you have Finale - deauthorize. It treats W10 as a new machine.  Also if you have Raxco Perfect Disk you will have to install it over the existing program for it to work.

I did an in place upgrade from win 7 64 bit to win 10 with sonar platinum installed a few months ago on an HP laptop and haven't had any problems. I had to re-license XLN AD and something else Omnisphere?