I've always thought that an advantage of PR is that candidates for a district's multiple seats could appeal to particular communities of interest within the district that they have an affinity to. If a constituent was having a problem with LGBTQ discrimination, for instance, they might have an LGBTQ rep to talk to, or at least could pick the one that they think would be most sympathetic. You alluded to this factor in this piece ("specialization"), although I don't quite see it reflected in your four 'Possibilities.'
I've always thought that an advantage of PR is that candidates for a district's multiple seats could appeal to particular communities of interest within the district that they have an affinity to. If a constituent was having a problem with LGBTQ discrimination, for instance, they might have an LGBTQ rep to talk to, or at least could pick the one that they think would be most sympathetic. You alluded to this factor in this piece ("specialization"), although I don't quite see it reflected in your four 'Possibilities.'