I started my apprenticeship in 1961. Back then it was Marples all the way.
I was never into all this hardness thing. Quite frankly it doesn't interest me. The chisel either kept its edge when using it or it was sharpened again to finish the job. We needed absolute precision so our plane blades for instance were sharpened and set after every few shavings on occasions which at times were silk thin. That was just how it was.
It's the same as when I recently bought a decent set of kitchen knives. The set I bought were Victorinox ( of Swiss Army Knife fame). Not terribly expensive but they sharpen like razors if sharpened correctly though some people whose feedback I read before buying them complained about them not holding their edge for longer than a month!? Others complained that they needed sharpening straight out of the packaging. Wow who would have guessed that!
When I use a knife for food prep I sharpen the knife with an iron every time without fail even if it is straight out of the packaging. In my experience no tool stays sharp indefinitely. If I pick up one of my chisels it's either sharp enough to do the job or it's sharpened until it is.
If you compared marples chisels from 1961 to mine, you'd sudden be into this hardness thing.
It's more interesting to me from a toolmaking perspective than it is using. If work is at the bench, I don't like chisels below 60. Older english chisels weren't usually under that. site chisels are (but they are also often made of steel that's very tough but not very strong - as in, they will absorb a lot of energy before they actually break, but they won't absorb a lot before they start to deflect - harder tools are generally opposite - it'll take more to deflect them, but then there's much less between deflect and break).
You can't rely on anything in the knife community - some of those guys think they couldn't pack a moose without 3V and then the next guy will say he uses 1095, and the guy after that will say 3V doesn't have enough abrasion resistance for a career guide (as in, someone in the US who takes people on guided hunts and then helps them break down animals to pack out). The next guy will come along in an apartment and boast that vanadis is just as easy for him to sharpen as 5160 - which is only the case if you don't actually use a knife and thus never have anything to hone out of an edge.
I have a thought about actual use of tools:
* how quickly and how well you can sharpen is first
* whether or not the tool or knife you're using is in a good hardness range for what you're doing is second
* alloy and all of the other money-attracting stuff is a distant third. Very distant. The second item is distant to the first unless there's something way off about hardness (using a 56 hardness chisel in hardwood is going to be a crap experience. Using one 63 vs. 61, no big deal. Buying a chisel that's 65 hardness if you're using a broken in oilstone will probably be unrewarding because the natural stones have particles around 62).
There are a LOT of people who haven't tackled the first start who love to speculate on the second and third star, but they usually start with the third without having a clue that varying hardness probably has a lot to do with their experience. In the knife world, it gets far worse as there are cases where a 55 hardness knife is better than 65, and then the opposite. But it leaves me scratching my head when someone gets some high carbide knife that they want to use for slicing, the knife has a high temper range that puts it around 64 hardness, and then they buy from a manufacturer who specs the knife at 57 because it's easier to not receive returns with the tip snapped off and it's a lot easier to finish a knife that's 57 hardness than 64 after quench.
A little bit TMI for some.
I would advocate for the average person to go through reasonably priced used tools that have residual value and stop when you find something you like. It may be the first one, it may be the third. There's no need to even know how hard they are if they work well with stones and then work well in use. Later marples tools often have flaws that fail that - my 10-chisel box set is an example. It wasn't expensive, the chisels appeared to be unused, and then I found out why. before I dump them back on the market, they will all be hardened to at least be usable (which doesn't even require removing the handles if done properly). It shouldn't be the case that any manufactured tool can be improved by a guy with a paint can forge who doesn't even take the handle off to temper the chisel.