Do I have to be "careful" when updating with the Manchester update to preserve Melodyne Editor 2?  I'd prefer to keep the polyphonic capability, even if I stay on Editor 2, versus upgrading to Essential 4.
 
I'm understanding the NEWEST Melodyne releases overwrite all older version, whether it's Editor, Studio or not.

looks like this thread is the answer..
http://forum.cakewalk.com...ssential-m3291700.aspx

Yes, Essential 4 replaces other Melodynes. If you upgraded to Editor 2 , DO NOT install Essential 4.
I read that only Studio 3 can co-exist with other versions but cannot confirm this.