I really don't get it. What's wrong with having the cake and eating it, if we actually can ? Majority bonus PR is infinitely more representative than any constituency-based system, and avoids most of its shortcomings.
But in a constituency-based system, every member of parliament can rely on a personal vote. He is supported by more people in his constituency than anyone else. That is a great thing if you ask me. The single MP is more independent in his voting, and, at least theoretically: No one is really save.
Tony Blair could have lost his super-safe constituency in Newcastle (right?, somewhere in Durham I think), if only a few thousand people voted another way around as they did. That is the charme of FPTP: No one is really save.
On the other hand, Schröder, Müntefering, Steinmeier and Steinbrück would have been elected in the Bundestag even if the SPD would have been down to 5,1% in 2009. No voter could have done anything to avoid that.
And majority bonus PR combines the non-proportionality of FPTP and the ultimate power of party bosses of list-PF.
