Just to clarify, the rear suspension on the GH2 isn't quite the same as that on the GH1. The GH1 had a whole beam axle that literally just went up and down. This meant that if one rear wheel hit a bump, the whole axle would pivot on its mounting points. This was why it handled so abominably badly.
The GH2 has a system more like that seen on the Hornet 1. Instead of fixed pivots, the mounting points for the rear axle were in spring-loaded slots, so if a rear wheel hit a bump, the mounting point could slide up the slot, giving the rear axle a degree of independent side-to-side movement, as well as up-and-down.
The GH2 had plain springs instead of the Hornet's rather natty and effective oil-filled shocks, however, so suspension location and movement was still rather erratic. That said, it was still a huge improvement over the GH1's more rigid set-up.