This is a pretty polarizing topic, but I'll start with what I do with my carry guns.
On all guns, factory sights get dumped for night sights (if not so equipped from the factory)
When I started carrying and was carrying a Sig P226 Mk25, I had a Sig SRT sear set installed and had some to the internals polished to smooth out (not lighten) the trigger. Done deal after that.
When I tried carryign a Glock for a stretch, it was night sights, a Glock NY-1 spring and a Glock - connector. The connector was polished to smooth out. Kept roughly the same factory pull weight, but took some of the mush out of it so it felt more crisp and positive. In my experience polishing the connector took a little bit of the gritty feelign away too. After the Glock turned out to be a flop due to it literally not fitting my hand (from index finger to pinky with fingers together, my hand is rather short despite having long fingers and my pinky sits quite uncomfortablyl on the last finger groove, I moved on.
Next gun up was an HK P2000 V2 LEM. Shot it stock (with stock white dot sights) for about 1000 rounds before making my minor changes. I had Meprolight night sights installed and made the following changes to improve trigger pull; installation of V1 light LEM firing pin block spring and V1 light LEM mainspring; I kept the heavier V2 trigger rebound spring. This brought the pull down from 7 lb to about 5.5 lb and is the equivalent of a factory delivered V7 LEM. I also swapped the standard P2000 mag release for a larger HK 45 release.
After the P2000, I added a P30L and P30SK to the HK rotation both wtih V1 Light LEM triggers. Both had factory night sights only change made was swapping the V1 light LEM trigger rebound spring for the heavier V2 trigger rebound spring to ADD a little bit of weight to the trigger pull and provide a more positive trigger reset as I noticed that after spending A LOT of time shooting my Sigs with the SRT sear, I would occasionally short stroke the trigger.
Lastly I land at my current carry gun, a Walther P99, for it all I've done is swap out the factory polymer 3 dot sights for Trijicon night sights and for a stretch I had Talon grip tape on the gun to give better purchase; it has since gotten ratty and been removed and I've been going without since. The trigger is very similar (albeit slightly smoother and lighter out of the box) to a Sig P22x with an SRT sear.
Now, to dispel a common misnomer, slight trigger modifications as above will not result in prosecution in a clean SD shooting. Heck, if you're someone who carries a Glock or M&P and want to drop an Apex trigger in rock on. Having had a tenure in the Attorney General's office and frequently trying cases against them now, I can positively say that they know as much about guns as I know about astrophysics...not much. Bearing that in mind, if the modification makes the gun do something it's not intended to do (i.e. my former murder client who modified an Intratec DC9 to slam fire), then it's an issue that can land you in hot water. If you're making a modification that maintains all safety values, etc. that are designed into the weapons system and the modification is something to enhance your ability to hit your intended target, no need to worry in Delaware. Further point of note, I would advise NOT using a competition type trigger in a carry gun since the adrenaline dump that accompanies a body alarm reaction is going to take away some of your tactile sensitivity; hence the reason I elected to modify my P30 triggers to be slightly heavier. So if you want to make a minor tweak to your carry gun's trigger to slightly enhance its shootability, go for it, but don't get too crazy. Be sure to maintain all safety values (drop safety, firing pin/striker block function, etc.) and to make sure that if lightening, you're not going so light as to be able to unintentionally pull the trigger when under stress.
