I'm going w/ a typo.

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If their D2 wasn't hardened to a higher Rockwell value than their 420HC .. the two resulting blades .. one of 420HC & one of D2 would sharpen w/ the same degree of difficulty .. which isn't true.

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Also, why offer the premium ATS-34 & D2 steels primarily on their upper lines .. if the less expensive 420HC would perform as well.

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No .. a salesperson compiled the catalog data ... imo.

I have been using D-2 for over 40 years. Love it! Have used it to build stamping dies, knives, and spinners for copper tubing. Yes it is hard to sharpen. Diamond sharpeners help. I prefer to draw it a little farther to about Rc55 as it seems to hold an edge a little better. To each his own though. 60 also works well for a knife taking less abuse. Doesn't rust quickly either. I little hard to work and machine until you are used to it. Much slower speeds with no lube helps.

Fred,

I tend to like it also.  That first sharpen may be a little tougher but the dang thing will stay sharp forever with just a little touch up now and again