His point is that dpkg is unable to support installation of multiple versions of a package. update-alternatives and having custom packaging (like with python2.6 and python2.7) solves some of this issue, but Gobolinux deals with it a lot better
Just had a look at gobolinux now - that filesystem change seems like a sledgehammer to counter the 'lack of ease' in tapping in the picture-hook problem of installing two programs.