Would it be a good idea to use Waves StudioRack Native with Sonar or Logic Pro X? Even when I'm only just starting out using Waves plug-ins (NLS, Scheps 73 and Codex)?
Or would it make things unnecessarily complex?
And what about the included EMotion ST Mixer?
Thanks for looking into this, guys.

I wouldn't bother.  For me, it was a PITA to install, and I can count on no fingers the number of times I've actually used it.  Sonar's FX chain feature works fine, and isn't limited to Waves plugs.
 
Cheers,
Eddie
 

+1, can't really imagine a good reason to use it.

Thanks, gentlemen.