Let me make an alternate proposal. Suppose that we want 600 congresscritters and the population of voters is 300M. Dividing A into B, we get a simple ratio of 500K to one. Let's allow them to sign up directly. No reason for it to be limited geographically. If you like Representative Archie, sign up with him. When Archie gets 500,000 registrations, he gets a seat. Even better, we'll let more people sign up -- if Archie is so popular that a million people sign up for him, then he gets two votes. We'll stop there to prevent too much power concentration -- more people can sign up for him if they like, but he doesn't get extra votes.
Once per period, all of Archie's constituents are surveyed to determine if they still like what he's doing. They can change registration at any time, but this is the most convenient time to do it.
If Archie drops below 1M at any time, he goes back to one vote. If he drops below 500K at a survey point, he's no longer a Representative.
I think we could come together with both Ideas and make a system that works. I like some aspects of your plan , but I would want to see a few modifications. Your extending into voting systems as well and I don't necessarily think your doing it the best way , but i _love_ the idea your putting forth.
So i realise why I like aspects of your proposal. Because it has a few of the principles of the Mixed-Member proportional  System mixed into it. I like MMP I really like it. I think that combined with a radical expansion of the number of representatives ( I think we should be closer to 100k then 500k, maybe as low as 50k ) would allow us to do many amazing things as a country. Also I would toss this wrinkle in. MMP is done at a state level and only state level political parties are recognized, and they are now official. They must follow rules to elect their leadership.