Hiya Matt,
you got a lot of questions there- some I cant answer, but will try to give some input here.

Overall the quality of design and manufacture of the Sport even to this day is still far and above many other springers out there. I think most collectors, however rose tinted their specs are, will readily admit it isnt perfect however.
I am a little doubtful on it being a scope killer though? I've had 5 of them and recoil always seems very acceptable to me? The breech lock up needs to be checked closely to esnure its good and positive. The safety carch issue is one where a repeated pull of the trigger when the safety has been engaged can in some rifles lead it to disengage and the rifle fire. I have a 127 where this is the case. I wasnt aware of this and found out thankfully with no harm done- and later read this is more common that first thought. As for remedy- well I am unsure really- there are others better qualified to comment.

Ive read that in some instances where the rifle has been unused ofr extended periods and the innards dry- this can lead to the piston head becoming perished and break down.

I do have one 124, but dont shoot it that often to make an meaningful comparisons between it and the 127s i own. All Sports have a modest recoil and a muzzle discharge that belies their power output. They really are quite a small punchy rifle with low cocking effort. Best do a trawl of sales on here and other forums to get an idea of sale values.

Like I said above- they are not perfect, but are desirable, collectable quality rifles.

good luck in your search.
Dave