Having taken both EECS 470 and EECS 427, I will agree that 427 is probably the hardest undergraduate class I took while at UofM.
However, 427 and 470 don't compare to EECS 627 (VLSI II). I would put that class up with any other class at any school for the amount of work and difficulty of material. I spent over 60 hours a week in the media union for the whole semester to work on the project, and unlike 427 where the project is basically your grade, the exams were something like 60% of your grade.
Then again, I now design circuits for a living and no course has taught me more so I guess it was worth it.