I am thinking to upgrade to assistant which will enable me to lessen vibrato effects in pitch-y vocals. I am not interested in anything but getting vocals tuned well-I move things around in Sonar, use human vocalists for harmonies, and I don't record out of tune guitars so don't need polyphony. But what I do want to do is deal with vibrato. So, Melodyne Assistant should be enough of an upgrade. 
 
Do any of you that have the better versions of Melodyne do extensive vocal editing (talking pitch only here)? 
If so, is the vibrato tool effective at a pro-level, or does it leave potential artifacts if you try to expand it enough to greatly minimize the vibrato?
 
Thank you in advance for not asking me to get better singers.
 
Thanks everybody.
 

Hi Michael.
 
I have Melodyne Studio and have used it on quite a few occasions to reduce vocal vibrato. In my experience it does a great job. Like most audio effects less is more, but used subtly there will be no artifacts.

Same experience here as tenfoot. Eliminating vibrato sounds weird but that's not because of Melodyne . Reducing vibrato works well.

Was about to write what Craig wrote.  I reduce vibrato all the time.
 
Interestingly, a lot of people who say they hate pitch correction software tell me they are glad to hear that I get good vocals without it.  I actually examine and touch every note: not because they are horribly out of tune, but because I want a specific sound that requires nudging pitches and times. And, of course, if something is out of tune, I fix it.
 
I can fix a vocal take with a good feel and bad tuning way faster than I can re-cut it trying to get a perfect take with the right feel.  For example:
 
Years ago, a Texas rockabilly singer you may recognize by his pale skin and sunglasses would record with me and we'd fill half the tracks on a 2-inch 24-track machine with vocal takes so he could go through them over and over again picking out the phrases that were best to piece together.  Thank God for Melodyne.

To be honest I find Melodyne's ability to deal with vibrato pretty limited. You can only increase or reduce the existing vibrato. You can't do anything about speed and it's tricky to even out if it's irregular. On the upside it sounds pretty natural unless you go to extremes. But if you had a deft touch with V-Vocal you could do more with vibrato.

Sanderxpander
To be honest I find Melodyne's ability to deal with vibrato pretty limited. You can only increase or reduce the existing vibrato. You can't do anything about speed and it's tricky to even out if it's irregular. On the upside it sounds pretty natural unless you go to extremes. But if you had a deft touch with V-Vocal you could do more with vibrato.

If you want something like V-Vocal's vibrato tool, flatten the vibrato and use the Sonitus modulation plug-in (set to create vibrato) as a clip effect. If you have The Big Book of SONAR Tips, check out the tip "The Secret Melodyne Essential LFO Vibrato Tool" in Chapter 5 on Melodyne applications. 

True, thanks, though I forgot about it I did notice that tip when it came around. It's not something I need very often, I just meant to comment on the OP's specific question. Melodyne itself, no matter how expensive the version, has pretty limited vibrato control. Not sure what the OP is expecting for his money but it's not like V-Vocal. Thankfully there's still Craig :)

For those that have Melodyne (especially an upgrade from Essential) I have found this page an excellent resource.
http://helpcenter.celemony.com/hc-2/
 
It saves trawling through youtube.

Awesome, thanks!

The old Vvocal has a vibrato tool to decrease or increase vibrato. It also has a pencil tool to draw out bad dips and such. Melodyne does not have either tool and is deemed inferior in my tuning tools. It's only great for poly stuff. Go back to the basics. (That is if you have a prior version to Platinum to get it from.)  Sorry to see it go.