Congrats on the new Shield. Handy, slim little single stack pistols.
You can find no particular shortage of uninformed and informed opinions about the relative value of tritium night sights. A range of difference experiences, too.
I wasn't a particular enthusiast about using night sights early in my LE career, even as a younger firearms instructor. One of the common 'objections' heard back then (80's & early 90's) was how they'd possibly let an attacker see you via the green dots floating around, especially on duty guns openly holstered on gun belts. Well, that argument got a bit weakened when I did some night shoot training in an instructor class in '90, and a guy with a Sig Sauer had night sights.
Sure, if he stood still and I could position myself at the right distance and in an ideal position, and I let my eyes relax, I could see the night sights within a few yards. I could hear him much more easily (jingling equipment, breathing, shuffling feet, rubbing clothing, squeaking leather, etc). Once a flashlight bean came around, my night sight and ability to find the itty bitty dancing & floating green dots disappeared.
In other words, not so much of a 'tactical/officer safety' concern as I'd heard promoted.
As time passed, and I eventually tried them again (I like to periodically re-evaluate my thoughts, training & experiences), I eventually discovered they could be very useful and practical in some circumstances where I found myself on an almost daily basis. I started ordering new pistols with them, and installing them on a number of my existing pistols. Not all of them, but maybe approx half of them. I tried a few variations, including 3-sot, front dot-only, stacked dots, different color dots and so on.
When were ordering some new general issue pistols several years ago I suggested we order them with factory-installed night sights. Pretty affordable as a factory option, especially when you're ordering close to a quarter million dollars of new guns.

Once those started getting issued and out in general use, we started hearing some favorable feedback from the troops about the new (to them) night sights.
I remember one young guy telling me that he'd discovered they gave him a quicker and easier sight acquisition when he made a high risk traffic stop at night. He particularly liked how much faster he could acquire the sights when the 'backdrop' was brightly illuminated, but he remained in the dark (behind the wall of light). He said he'd been surprised that it was noticeably faster than when he'd just used to acquire the non-tritium/3-dot sights against a background that was illuminated (and the sights were just a black outline against the bright background).
Now, granted, using tritium sights in bright daylight conditions may not be as quick or as handy for some eyes (mine included), especially if the thin white line surrounding the lens (covering the capsule) gets fouled and covered with a dusting of grey/black. Then it's like just using plain black sights, instead of being able to see 3 starkly white dots aligned and imposed over the intended target. (Same thing can happen with neglected and heavily fouled 3-dot painted sights, though, too.

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Newer sight designs have given us some options that help reduce this sort of issue, though. Brighter colored paints, light reactive paint, plastic rings and fiber optic tubes are some of them.
Any discussion of night sights probably ought to include at least some passing reference to the fact that it's only the tritium capsules that are illuminated .... meaning not the actual intended target. You still need light to see and identify what you're aiming at and intending to shoot. Light sources are still important, including ambient, environmental, hand-held or weapon-mounted. Not necessarily a bad idea to get a better understanding of how to employ any of them, and some level of training in their use.
I have a few pistols in which the tritium capsules are at, or approaching, the end of their service lives.
I might replace some, or maybe send the sights for new capsules (since I have a couple sight pushers and some brass/nylon drifts, as an armorer), but I'm not in a particular hurry.
I'm not working full-time anymore and finding myself in places and conditions every hour or so when I originally found them handy, and I still carry hand-held lights with me (if I'm going to be out after dark, but also if I'm going to be inside any commercial buildings where a power failure could be inconvenient).
I like them on my pair of M&P340 snubs, which use the standard size XS front night sight dot. Handy. Faster and quicker to align in normal light (because of the bright plastic ring), and useful in reduced light conditions (better than my 649, 642's, 36 and 37 with only painted ramps).
I guess someone could say that I'm probably an "either/or" guy when it comes to night sights nowadays. I like, have and use them on maybe half my retirement weapons, and still manage to get along fine using the other half without them.
Or, maybe I'm just lazy.
