My 92FS was older and had the steel trigger. I installed the Wolff unbreakable trigger return spring and haven't thought about it since. The Wolf unit is a good design and drops right in no problem. Instead of the OEM spring, it uses a coil spring set-up to push on the back of the trigger itself. That's why the older all steel trigger is required. They also have different weight springs. I installed the standard weight spring, and it didn't feel any different at all.
The OEM spring seems to work fine until it just snaps. You can flip it around and use it backwards (designed to do this) until you get a new one in. Obviously, you have to take the gun all apart to do this. If you're getting a sluggish trigger return, it's likely some other reason than the return spring going bad. Probably just dirty, or some old lube has turned to gunk, or brass particles in there or something simple like that.