Who wants to carry around another kb in a OMB act just for VH? might be ok for studio work playing in Vocoder mode..
That Lewis video is few years old. There has since been the VP-770 keyboard and lastly the VP-7 module with improvements to the VH engine. I believe Roland developed the original variphrase technology, and their expertise transferred over nicely to their VP products. Far ahead of Yamaha, Korg (T C Helicon), Digitech in regards to the gender and pitch stretching technologies. Virtually no warble or digital artifacts in the processing on the latest VP -7 unit. The VP-7 choir and Jazz Scat voices are not that shabby either, and can play over, layered on top of any of the Tyros 5 sounds.
The point is, you can get even better results with the little 2 lb VP-7 unit in variation mode, that was carried over from the previous VP-keyboards.
Setting the Tyros 5 to AI Full Keyboard fingering for your chords, you can still run full (vocoder) variation mode and still control your style play, multipads, ensemble, plus switch on-the-fly during a song to Human Voice/Vocal designer mode on the VP-7 or that robotic vocoder mode.
Not only for studio, but for live performances. I have a little aluminum bracket that fits into the Tyros 5 speaker mounting holes that screws onto the mounting holes on the less than 1 KG VP-7 unit. What is more portable than that, plus in direct visual range from your playing position and easy to manage the controls.
For a gig, one Tyros 5, one VP-7, good mic and stand, and proper powered speaker configuration for the venue size. No second keyboard or laptops.