I can give you personal experience with using night sights.
While at Thunder Ranch during several night drills, I found that I was shooting tighter groups in low light than I was during the day. That green light bulb just yelled "Look at me!!!" and I did.
IMO once you actually use night sights in the lighting conditions they were designed for you'll never be without them.
As far as using a light, I have a SureFire 6P that I carry anytime I carry my 1911, (which is all the time) and I practice the "Harries Technique" in utilizing it. I find it to be stable and accurate enough for defensive work.