I really appreciate all the information, guys. It's convinced me that most situations where Melodyne is used is for one-note-at-a-time stuff (monophonic?) and so Essential or one of the other tools I already have will do the job. For polyphonic stuff, it's far easier and faster to just talk myself into doing another take.
With the other tools I already have available (AudioSnap, V-Vocal, Melodyne Essential and Pitch Shifter) I think I can cover just about any situation that will arise for me in the foreseeable future.
What's really weird is that my wife told me I could spend the money on the upgrade and I'm ending up turning it down. But then, I'm likely going to need nearfield monitors in the near future. I'm using a pair I borrowed right now and I'll soon have to return them, so the money will go toward that.