How do you justify the fact that only some of the students get the pleasure of an in-person grilling? Or, am I completely misunderstanding the process you're going to be using?
There's still a scaling problem, but I think it makes the ~200 student classes we have now more feasible than 100% autograding. I also like the other commenter's suggestion of coming back to interview certain students each time, if they need it.
A lot of stuff you learn and the way you learn it isn't necessarily pleasant, but frequently you still have to do it and you really discover 20 years later why it was needed.