The quest for a portable piano has been around since the invention of the Fender Rhodes and the Wurlitzer. Of course, neither of these actually sound like pianos... they have a pleasant sound that is 'piano-like' but in no way are they a substitute for the real thing.
Several companies tried all sorts of things (including some fairly horrible electronic things) but it wasn't until Yamaha released their CP70 'Electric Grand Piano' in the mid-'70s that I had something approaching a 'real' piano that could be toured around and amplified easily without any difficult mic techniques.
There were three models in the product's lifetime... the original CP70 (73-note keyboard) which was superceded by the CP70B (with balanced outputs) and the CP80 (a full 88-note keyboard version).
All of them featured true grand piano action keyboards which, if you were a real piano player, were a delight to play.
In their brochures, Yamaha claimed their electric grand pianos were "compact" and "portable". I am not convinced! They measured at least 57 inches wide by 45 inches deep (front to back) and weighed as much as 313lbs! I guess that at a time when bands were going out with Hammond organs, Leslies, CS80s, multiple MiniMoogs, Mellotrons and so on, the CP piano was comparatively 'portable'.
To make it easier to transport, the CP piano dismantled into separate units with the strings and frame in one case and the keyboard, legs and sustain pedal in another (right) which made it slightly more managable. It was re-assembled with some clever lock catches. Even so, it was a two man job to cart it around.
On a long tour, however, it wasn't just roadies you needed to employ to look after the thing. Because it was a 'real' piano, it had 'real' srings and so needed regular tuning by a qualified piano tuner especially when the instrument was being thrown in and out of trucks! Because this was a luxury that not every one could stretch to, the CP70 gained a reputation for being a bit of a 'honky tonk' piano because many were heard slightly the worse for wear and out of tune.
This reputation was not helped by the fact that one of the CP piano's more famous users, Peter Gabriel, always ran his CP through a vintage Roland Chorus pedal! It's a shame really because the CP is actually a nice sounding piano when looked after.