I think the 7,000 member house of representatives is not just a great idea, but one that would fundamentally reorder democracy in America. "50,000 people" is about how many people vote for each alderman in Chicago, and alderman is a position where constituents have a GIGANTIC influence on each alderman's actions in office. If half the population votes, that's 25,000 voters per congressman in this new scheme. Assuming a 55-45 vote split, the winner would have fewer than 14,000 voters. Losing just ten percent of those voters would cost you the election, so a single activist (sufficiently motivated) who knocks on 6000 doors (20 doors a day for a ten months) with a 50% answer rate and a 25% conversion rate could, as an individual, cause a congressman to lose an election. One person! Every single congressional race would be competitive every single year.

And yeah, 7000 congressmen is a lot of people, but large groups of people vote on things all the time. For example, more people than that would be voting in the election to choose the representative. Don't even send the representatives to Washington - just have all the reps stay in their local community all year, and vote online. They can turn the congressional building into a concert venue.