It is absurd to credit the Gen 4 Glock with the reputation of the previous generations. The redesigned recoil spring is every bit as relevant a change as a new engine design in a car. Similarly, changes to extractors are relevant. The track record for the Gen 4 Glocks started with the release of each model-- NOT with the launch of Glock.
"Of course it's reliable" works with Gen 1-3. They have earned that. The Gen 4s have about a two year history, marred with hiccups in the early going. As far as anyone should be concerned, the Gen 4s are still in the "prove it" stage.
Currently Own: Beretta PX4 9mm, Glock 23 (Gen 4), Glock 19 (Gen 4) x2