Fantastic kit, for the day.
I used the Compass and many of the later GRiDs. The magnesium case was heavy but when a london bus drove over one of our GRiDs the screen (and modem) survived and was swapped into another machine! Try THAT with ANYTHING today.
Their biggest drawback was with the batteries and power supplies. Battery life could be 30 minutes and with the later machines the power brick was encased in perforated steel and fitted INSIDE the magnesium case. The temperatures could, and did, raise blisters and in one case burned a carpet.