tstop4me,
You are right, Sid´s gauge "acceptance criterion's" are designed for JW and MK blades, but it´s handy tool to see roughly difference between the different blade brands, models and what happens when you sharpen blades. When you have measured enough many blades, you will start to know which are normal touch point lengths for different blades. What was my point is, that people might change from Wilson blades to new Ultima blades because Wilson blades were worn out, but in reality they might get very similar profile even the Ultima blades are new and they have huge "sharpenable zone". I am not sure if people are more worried about steel hardness or blade profile changes. What I see often is that of young skaters buy used Coronation Ace blades, which are worn out. When I mention this, they might come next time with brand new Ultima blades without understanding that they did actually buy blades with almost identical profiles as they had in the worn out Wilson blades.
I haven't kept any Step blades on my hands, so you can be right that there is sharpenable zone marking. However I would not be so sure about it, if hardening ends in to that area. Example in this case, if I have understood correctly, nicklaszlo believes that he can remove more material from Ultima blades than from Wilson blades, because chrome has removed from the wider area. Or maybe I have just understood wrongly.
I would like to investigate how blades are hardened / tempered, but I should sacrifice brand new blades for that study. Unfortunately I am not rich enough to do this study.
I guess I was misleading twice in the Matrix blades. Runners are not polished and it is Legacy which do have at least parallel side´s. Parallel Matrix runners do not have any sharpenable zone markings. Matrix runners with taper machining (milled dovetail shape) do have kind of visible sharpenable zone marking. What I tried to say is that in the parallel Matrix runners you have only plain grind side surfaces without any sharpenable zone marking. Even their steel runner would have same hardness all the way to the aluminum frame, other things will limit the blade lifetime. This you also mentioned and this is the message that I tried to highlight in my previous post and when was referring to Sid´s gauge.