Well, the reason I push towards optics and SFP's in the 10 Gig primer is because it works pretty similarly for 25G, and 40G/100G are just QSFP variants, so they're really the same(-ish) too.
However, yes, point made. The problem is that I don't want to overcomplexify the topic and scare off newbies. Anyone who's worked with category cable knows that Cat5, 5e, 6, 6A are all slight variations on a theme and that gigE works fine on all of them, sometimes even on Cat3 for sufficiently short distances. It probably warrants a physical media topic. Damn, I just had something else worth touching on and I lost it. :frownyface: