Tom,
From what I've heard, both from the folks on the forum and listening to both, plus using the Vocalist VR, the difference is almost insignificant, and the increased cost of the TC doesn't justify the slight difference in quality. As for live performances, I seriously doubt that anyone in the audience would notice at all, especially if the devices are used correctly, which is sparingly at best.
Good Luck,
Gary
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PSR-S950, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, and lots of other silly stuff!
K+E=W (Knowledge Plus Experience = Wisdom.)