Never got the chance to work with that generation of Balantynes, Robert. The VIPS were very popular with Tom Moyer. I was at several of his new builds, and witnessed those machines jump all over the screen, straight off the truck. Later, I had the joy of working on them. In spite of the efforts of some very qualified techs, I never saw a VIP that had as stable an image as an average Century. Too bad, really... they're quiet, built like a tank and handle film well, but those framing couplers are the worst.
Disney, who I'm told had a whole bunch of them in their theme parks, took the framing couplers out altogether and still had to rebuild the machines every 500 hours or so to keep the vertical jitter down.