I'm not sure that this legal challenge is going to get anywhere, but it does highlight an important point. In addition to the fact that our relatively small legislature means that most Representatives have too many constituents, the system modestly disenfranchises voters who happen to live in districts that are not quite large enough to be split in two. Montana, for instance, has 80% more residents than Wyoming, but both states have exactly one Representative.
One question is whether such a system would tend to strengthen or weaken party discipline. That's harder to know. However, considering the fact that most parliamentary democracies have minor parties that occupy a few seats, one might expect that in America's two-party system, factions would form that replicated the effects of minor parties. To an extent, we already have this today, with the Progressive Caucus, the Republican Study Committee, the Congressional Black Caucus, and so forth.