Last year I was walking at night down a really dark stretch of road when I heard something go through the woods. Not sure if it was a deer or a dog, I drew just in case, it was really close, probably 10 or 15 feet. I couldnt see the sights at all, it was just the perfect place for a nuclear sight.
Lighting them up with a tac light will destroy your night vision, and make your position visible. Not the best combination.
First off, using a tactical light will not destroy your night vision, if its outside, and pointed away from you! If you are inside yes, because everything reflects (not just mirrors and glass). Now light will distort your night vision anywhere, SLIGHTLY in this situation, and lots inside, but here is the trick, close one eye. Or better yet, if you can cover one eye. Very simple.
Next point: night sights are pretty much useless. One, you shouldn't be practicing defensive shooting (at least at close distances, which most defensive shootings happen at close distances) with the sights. Although this is just a personal preference, but one that most professionals agree with, using your sights waste time in these situations, and tend not to make a difference. Another GREAT reason why night sights are useless are if you do use them, after your first shot you become, basically muzzle blind, and can't even see the glow from your night sights. So basically night sights on pistols are completely useless and serve no purpose. This is all purely my personal and humble opinion. It is also worth what you pay for it.
Many in the LEO community don't like laser's, they somehow see it as cheating, or somehow taking away from their manhood. Whatever. Do I own any lasers, for any of my firearms? No. If I could afford a LaserMax for my EDC would I buy one? Yes. Its funny, you can ask most LEOs, so do you have Night Sights on your duty weapon, and do you like them? Most will say of course, they are a must have. Then ask them, have you ever actually used them, I mean think about it, when you have pulled your weapon, in a low light situation, were you looking down your night sights? They will most likely say well no actually. Then ask them, would you ever use a laser? Well of course not they are stupid, and for wannabes! Then say, oh I see, so if you were ever in a true, SHTF situation, say taking automatic fire from behind your squad car, no backup, suspect approaching, and your running low on ammo, you wouldn't wish you had an accurate laser, with the proper training on how to use it? He/she would of course answer will since you put it like that of course I would use a laser in that situation, and would want one then.
Long story short, you don't NEED night sights or a laser, but if your going to get one or the other, I personally recommend the laser, and if your going to get a laser I suggest a LaserMax, just because they are more accurate, and INSIDE your pistol.
My $0.02. Start up the flame thrower!
ETA: Also this should go with out saying, but I will say it anyways, everyone that carries a firearm for self defense (in side or outside the home), should have a flashlight with-in reach as well. At a minimum just a flashlight, personally I keep at least a 200lm strobe (and a 800lm, yup 800lm, strobe at home). You don't have to be rich and buy name brand, do a quick ebay search, and you can find cheapo hong kong ones that take AAA's (not 800lm ones), but still VERY bright hand held flashlights.