Warning about breyton490 posting about messing with what he called the candy cane bend (actually is the sear engagement loop; sear cam lobe; shepards loop). Changes to this loop can mess the timing of the striker blocker clearing the striker. You can get the striker to release, but if the striker blocker has not been lifted high enough, it will not clear the striker, and the striker will not contact the primer (no bang). It could also cause the striker to partially hit the blocker, but not enough to completely stop the striker. So it might cause the striker to lose inertia (hitting power) and not strike the primer will full pressure, causing some light hits.
The Apex FSS would be a big improvement, but costs $180. It reduces trigger pre-travel, pull, and over-travel. A trigger just to reduce a little pre-travel/take-up would not accomplish much. The more important reduction of the trigger travel would be to reduce over-travel and reset. Pre-travel to reach the start of the sear pull is a one time occurrence, when you fire. After that you just need to get to reset, as fast as possible, to get the next shot off.
Reducing trigger over-travel and reset will reduce trigger travel on all follow up shots. Not only will this allow firing subsequent shots faster, it also reduces gun movement and allows faster target acquisition. Competition shooters will verify this.
Check out this video I made. I installed only the Apex sear and striker blocker, and added my own over-travel stop.
Link:
M&P Shield With Apex Trigger and Over Travel Stop - YouTube
Bob