Keep in mind though, that any system which makes it feasible for Greens to win seats is also liable to make it feasible for far-right parties to win seats.
Honestly, that's fine. I might think most of them are absolute nutjobs and a great deal should probably be in jail for some of what they propose (mostly the bigotry and disenfranchisement/corruption stuff they like to pull, off the top of my head), but if we're going to do this democracy thing they should get due representation -- their vote and representation shouldn't be buried under FPTP bullshit any more than mine should.
As is, when a left candidate in their area gets elected, they lose representation and have their vote effectively stolen from them just the same as a leftie does when a right-wing candidate wins their area. It would be really goddamn nice if that weren't so. Changing from the FPTP system might not be a silver bullet, but it would damn sure be a nice 9mm to the knee or something.