There ain’t a damned thing wrong with it’s slide. It has been proven over and over and over again to be a reliable, accurate, effective military sidearm.
since the sidearm is never a primary weapon in the military, i don't think it says a lot about it's reliability.
there is a reason the P35 was droped by the SAS and the FBI HRT...it didn't hold up to training
the real test, for hard use, is competition. when the South African and Rhodesian IPSC teams won the World Championships with the P35, competitors looked very hard at the benefits of the P35 and asked the team members about it's abilities. their answer was. "it was all we had available...they barely last a season and need constant work"
a spoke to a USPSA Grand Master who was also a well known gunsmith about building me a hard use P35...like the FBI HRT pistols...and he advised against it as the slide was too light and moved too fast to hold up, because it was designs as a military sidearm. the P35s which have been strengthened for the .40 actually hold up better