Today I put an end of a True Temper Platinum tube .8mm wall to the grinder just to compare it to the .9mm wall of the RC2 tube. That .1mm makes a huge difference on how easy it grinds and how quickly I was able to grind material away. My initial thought was the harder material would have been more difficult to grind, but that was not the case.

No way, an extra 12 % is nothing. Probably not even measurable as against other factors. If it ground more easily, it was the metal. Possibly the tubing isn't harder; doesn't air harden during grinding; or there are things that make soft materials harder to grind within the composition of metal that are not attributable to hardness. The latter is common. For instance materials that create stainless are often harder to grind.

One way to tell if materials are harder than others is through filing. If a files are not abrasive, they cut, and they can gauge materials, there are even special files that measure metal hardness, but any file should let you know the relative hardness of two side by side metals.

I use hand tools to create miter shapes and have found that the old Platinum main tubes were darn hard; noticeably more difficult to file compared to something like Zona.

I have to wonder if there is something unusual with this particular tube as I took a hand file to it and didn't think it was all that hard to file away. Ordering a different tube anyway, so this won't be used, but I do find it interesting.

I was wondering if it was really hardened