That's a question that comes up in any mixed system. People can say there might be an issue with having tiers of members of Parliament. It isn't an issue in Germany. It would be something to which the political culture would have to adapt. The idea of a mixed system is used in a lot of other countries. At the end of the day, I don't see having different types of members of Parliament as being a big issue.
On October 5th, 2016. See this statement in context.