Here's my comparison of the Rotary algorithm of the Eventide H9 with the Ventilator II from Neo Instruments. Both are used in stereo in the effects loop of my Axe Fx II. I'm showing the Slow, Fast and Brake settings on both.
I'm playing my Yamaha SA2200 guitar through the Axe Fx II set to a Bogner Shiva amp model with the Messiah V30 IRs.
The chords I'm playing are from Russel Ferrante's (Yellowjackets) Revelation. The second short part is from the intro of Bluesette (Toots Thielemans)