I have had an HW77 rifle in 0.22" for the last 30 years, which I have played with on and off throughout that time.
I have put a few tuning kits into it, fitted an adjustable butt plate, had a comb riser fitted and spent hours looking for the perfect pellet.
After rekindling my enthusiasm for airguns a couple of years ago and lusting after the HW100S rifle in the magazines I bought one in 0.22" to see if they were as good as they appeared.
What a piece of engineering! I bought it some toys to do it justice - a Harris bipod, a new side focus scope on the lowest possible mounts and another adjustable butt plate to get the perfect gun fit. I bought the pressure gauge kit and set the regulator pressure and twiddled with it when it needed turning down. I oiled the walnut stock until it glowed.
However, it is still the '77 that I pick up most evenings when I go out into the garden to wind down with some quiet time, target shooting.
You are right, it is a big, heavy old gun but it has stability and is a much better shot than me. Mine has the 25mm internals which I suppose helps too but it is a world apart from my wife's lightweight, jumpy 0.22" HW50S.
When I get everything right, it will put pellet on pellet at 30 metres and 5 pence piece groups are not too hard to achieve at longer ranges. I really feel a sense of pride when I shoot it well, rather than "cheating" with the PCP!
I would be upset to see the HW100S go but they'd have to take the '77 from my cold, dead hands!