This is an issue with the pitch flex algorithm, on the h9 and pitch factor, the tracking is slow compared to the line 6, digitech, and ehx  "whammy" effects. I use the line 6 pitchbend for long sustained note soloing, I've tried without success to replace the unit with eventide products but the "ramp-up-into-the-note"/portamento tracking just doesn't cut it.

 In fact, it the only reason I have a big huge clunky line6 m5 on my board just for whammy effects.

 Kind of a bummer considering how "highend" eventide is, that a low end competitor's product  harmony effect performs so much better.