Well, I guess I can put two more bits in here...
The HardCore grinder was designed with CAD (computer aided drafting) and then machined from a solid block of 6061 aluminum with CAM (computer aided machining).
This is a hell of a process that anybody in either Engineering or Fabrication can attest to.
You get very exact tolerances.
6061 is the aluminum that is touted as "air-craft aluminum." It is tough. I built the skid plates on my four-wheeler out of 1/4" 6061 because it's DURABLE.
The alternative material would most likely be cast iron or the thin sheet metal crap that most companies are producing presently.
I LOVE my 960 variable, but with the current situation, I would get the HardCore.
Oh by the way, Burr King is a huge company that has long been a part of the grinding/de-burring industry. They still have a whole line of grinders and tumblers, but nothing geared toward knifemaking INTENTIONALLY (as was the 960 series).
My grinder is the center of my shop, so I feel the heavy price-tag for a quality grinder is quickly paid off. You will NOT regret forking over the cash for variable speed...
Nick