I think Mark McGowans' circle route proposal was a much better idea because it would serve both as a circle route and as a direct line to Perth all in one. Perth needs circle routes much more than the obsession with serving only the CBD. People need to get to work in places like Malaga and Canningvale and most of them probably live in the middle to outer suburbs. They build railways to solve congestion on the freeway, but don't do the same on Tonkin, Ried and Roe Highways.
Alternatively, they could build a light rail to Morley instead of an expensive underground heavy rail. Or even better, they should do both and connect up at either Malaga or Collier road. That would be a part of a proper network that would make it possible to get around the metropolitan area without being forced to rely on your car 99.99% of the time.