I bought a .22 Mk.1 from Thomas Turner of Reading in Mid to late 1973, even though Phil Bulmer in his 'strip' article sates they didn't come out until 1974, so would think your date for the MK.11 would be correct.
I would have thought the claimed reduction in muzzle noise with the cocking aid in situ, would be down to the aid slightly shielding the user from the muzzle blast.
I still have a few Scorpions in various states, plus a box full of spares, including a few hammers, which I must sort out and list one of these days.
I'm of a similar age and I too don't find the Scorpion that easy to cock any more.