Our former colleague, Louis Massicotte, who is now at Université Laval, worked with Quebec's committee. He's well-versed in Germany's system, having visited a number of times. He consulted with members of Germany's parliament and found that the system worked very well.
The responsibilities are divvied up. Voters can seek out the member for their own constituency or one of the list candidates from the party they support. Candidates prefer to be elected in a constituency, but if they aren't, they can be elected by being on the list. What they do, then, is try to make themselves known to people by working for them, so that, if one of the constituencies has an opening the next time around, they can run.
Mr. Massicotte didn't find any contradictory elements or problems with having the two types of MPs.