I guess I can ask you directly: how much time do you spend interviewing people, not counting the work-samples you already require?
As for suggestions, it's really about the next year. Unless you've already been doing this, you have to find people, and place them. And that means working not only with the programmers, but also the companies involved. Part of that would mean coaching them on how to use your system. You want to destroy the current tech interview process? You have to replace it. You want to remove the tech portion? Then I think the best way right now is working directly with the companies you are placing people with. They need to play by your rules, and a year from now is when you'll have a better understanding of where you stand, as the person you've placed is hired, and still employed.
Obviously there is more than just one candidate and company, but unless that happens, I don't see a company just buying into your system without keeping it's own. So you need to teach them what it is you are providing, and what they should do to maximize interaction with the candidate. The interviews will still exist: I want to meet the person I'm working for before I show up. But instead of dealing with white boards and ping pong balls, we are having a conversation about my potential future with the company, and what I can bring to the table.
patio11 said it: "we’re here to destroy it, and create something new and better in its place."
A job interview has two sides, the applicant, and the company, and if you want to destroy the interview and rebuild it, you have to do it with both sides at the same table. Otherwise, you aren't destroying anything, just adding more red tape before anyone gets to the table.