Great writup!
I have a relatively long (1/2 mile) gravel driveway to maintain and I've tried a few methods with varying degrees of success. I have never used a box blade though. Here's my thoughts:
ATV with DR Power grader...it works, but is not ideal for longer driveways or ones that need to be rehabilitated. It doesn't break up hard pack well, probably due to it's relatively light weight. It takes a large amount of passes to get the job done. Overall OK, but for the money, if you have a tractor...I'd go with it.
Tractor with 4' LandPride grading scraper....effectively does the same thing as the DR power grader, but much, much more effective. It has aggressive scarifying teeth than can be adjusted to rip up the surface (if necessary) and is has a few cutting blades that allow the churned up material to flow out of the "box" and lay smooth. Overall, a good tool. Takes about 5 or so passes to finish the job.
Tractor with 5' Harley Rake....awesome. I rented a 4400 with the harley rake to rehab my lawn...when I was done I decided to give it a try on the driveway. In two passes, it was totally smoothed out, "de-pot holed" and smooth. I can't say enough about how well this unit worked. I just wish they didn't cost 8K. I might try to find a used one.
-Mark