I have only lived in the Western part of Germany for a few years, but mostly, Statsis biggest tool was fools and children, as well as surveillance gear. "Ratting out" was not really the same big deal since there was not that many who actually did the ratting - most of thoose who did was already Statsi members who had a big influence in everyday life. While former Statsi Informers where arrested, charges was dropped (Beeing a member is not illigal). A country of 17 million had 100 000 Statsi mixed into them. Compared to Soviets 480 000 KBG Agents or Gestapos 40 000 (who watched over 80 Million), this is a big ammount of people.
Regarding the files, some are still classified, others was taken away with Western Intelligence agencies during the first hours of the looting of their headquarters. Any major spineless rat ought to have figured this was a good time to leave the country by then.
It is worth noting that many wanted the files to be classified to avoid just the kind of actions you describe above. However, in 1992 the files was declassified and anybody can request to have their Statsi act sent to them. However, it is impossible to say if theese files contain any names of agents who may have reported above-mentioned activites.