That delay, insignificant as it may be, is still present in today's TOTL models. That was one of the reasons I purchased the TC Helicon Harmony-M, which eliminated the delay, and the overall harmonies sounded superior to those found in the onboard selections. However, I have modified some of the Mic Settings for the onboard vocal harmonizer and was able to get some really good results, and additionally, the number of vocal harmony options were far more varied than those offered with any of the outboard harmonizers I've used in the past.
All the best,
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.)