What would the effects be within the House if we roughly tripled its size?
It's hard to see a lot of advantages. The kind of Members of the House that we want are serious legislators. But it's unlikely that the House would have triple the number of committees and subcommittees. In other words, on the majority side, we're going to produce more back benchers. Now, back benchers do have a useful role to play in Congress -- Congress needs its cranks -- but I think we would be hard pressed to say that there's a shortage there in the 435 person House. And that's on the majority side; the minority (GOP now or the Dems during their dozen out years) never has any shortage of showboats.
The fundamental bargain that Members of the House are willing to make is a large voice in a narrow policy area in exchange for no voice in all other policy areas. That makes sense for them for electoral reasons, because their constituents presumably have a relatively narrow set of interests. And it makes sense if their goal is to make policy, because in a large body one can have a greater impact on policy by having, say, a 1/4 say in one area and none in other areas instead of having a 1/435 say in every area. Make the House larger, and the logic for the trade-off is only that much stronger. Members' interests are going to be even more parochial and narrow. Is that really what we want?
At the same time, the needs for coordination go up in a very large House, which will tend to make the party leadership even more powerful than it already is. In 1950, I could see a strong argument that reforms, even dramatic reforms, are needed to empower the party leadership; I think it would be very difficult to make those arguments today.
I'll save the summary for one more post.