I would recommend that you not bother with the Wilson trigger spring dingus. I tried the reduced power version when I did my first Beretta 92 trigger job. Initially I installed it as it came from the package. I'd already polished everything else up prior to installing the trigger dingus, so the trigger was smooth. The TCU turned it into a gritty, inconsistent POS. Kind of Like an old S&W Sigma, but lighter. Yes, I was using a steel trigger, not the plastic coated one.
The sides of the TCU housing were rough, so I took it out and smoothed the sides up and polished them, as well as the insides of the pocket in the trigger. This made a marginal improvement, but the plunger in the TCU still wanted to bind in the housing when the trigger was pulled. I used polishing compound in the interface between the plunger and housing and cycled it a bunch of times. It was pretty much a mirror when I finished. Back in the gun...... still crap. Switched back to the original style trigger return spring and was back to sub-6lb DA trigger bliss.
I think the design of the TCU is flawed. If you look at the geometry of the Beretta trigger system and the TCU, pulling the trigger will induce a small bending moment on the plunger of the TCU, which will make the housing and plunger tend to bind up. I wasted a couple hours trying salvage mine. If you're concerned about trigger return spring breakage I'd recommend using the Wilson Chrome Silicon springs and changing them out from time to time.