I have played with both the TC helicon in the Korg PA1XPRO and the harmonizer in the G70/E80. I think the Roland is by far the smoother of the two. I have found that the Yamaha and Korg require me to "eat" the mic in order to not have any anoying slip ups in the vocals and when I use the Roland, I can sing more naturally and not have to worry as much about how close or loud I sing.
There is a demo mode on the Roland with a "pitch correction" demo where you sing the song Amazing Grace and the pitch correction is dead on perfect. It doesn't matter what pitch I sing, the melody is perfect.
In playing midi files, you need to know how important it is to have your melody track (the track the vocal harmony will follow) be as close to how you sing as possible. Another words, if you were typying in text for a midifile and you want the words to scroll while the song plays, you want the words to be slightly ahead of when you need to read them so that you are always able to look ahead a little.
With vocal harmonizer used for pitch correction, you would want the notes to be there if you anticipate your singing and sing the note just a little before or later in the song.
In the world of recording, there are a few really high end software pitch corrections applications out there and there are studios's that higher proffessionals that know just how to use this software to come into the studio and apply the vocal software just right. It's not that easy to do.
My point is that if you want to use pitch correction, the Roland has done a very good job without having to spend lots of time and money to get it just right.


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George Kaye
Kaye's Music Scene
Reseda, California
818-881-5566
www.kayesmusicscene.com