monoblock vs. hingingI'm not sure I understand the question.
So far as I can tell, all of the "classic" 4-buckle overlap boots have a hinge of some sort. Typically with racing boots (whether the full-on "plug" boots, or the standard retail racing boots) the upper is riveted several or numerous times, which disables the hinge to a large degree.
Your question seems to assume that plug boots have a hinging design, while retail-model race boots have something else. So far as I understand the word "hinging," I'd call them all hinging ... if anythiing, the plug boots are less "hinging."
I'm not sure what monoblock means. There's a review (repeated numerous times on all the websites that crib the same reviews) that throws out the word "monoblock" to describe the Tecnica Icon XT. I don't know what the writer really meant. It may have been a sort of rhetorical flourish aimed at saying they're really stiff and the hinge doesn't move much. But they obviously have an upper and lower part (they're even different colors!) and have a hinge (it's right there on the side), which probably hinges about as much as any similarly stiff racing boot.
"Monoblock" to me brings to mind the old rear-entry boots, which is another thing entirely.
As far as I know, the principal differences between the plug boots and retail racing models are: (i) stiffer, (ii) thicker shell, (iii) thinner liner, (iv) lower volume generally, (v) less "foot-shaped" last. Also, they're probably less likely to have various doo-dads like cantable soles, adjustable flex, heat-formable liners, etc. It's assumed you and your fitter will customize them to your liking the "hard way," with grinders, shims, heat guns, knives and the like.