Got this product at some daz sale around christmas...now I've tried it and want to share my experience...

http://www.daz3d.com/real-lights-for-daz-studio-iray

This product comes with different iray emissive light shaders, normal bulb light, fluorescent, magnesium, some neon and even campfire, but no "props" here, only light shader presets.

I have some older archictectural props which have only 3delight light setups or no light setups at all, e.g. I used it for an clothing shop by 3-d-c.

This has some build-in ceiling spots on which I applied these shader preset(s), these build in spots all share the same texture and so it is really comfortable to try different (simulated) light sources and also adapt the shader's light temperature and brightness with just changing it at the applied shader.

Sure you can fumble point lights in all the build in spots or make your own mesh lights (or even do some individual lighting setup for each scene), but in my opinion you can do some "basic" lighting setup much easier and more comfortable with this product, for me really a nice to have...especially for upgrading old 3delight light sources.

P.S. Depending on the surface you apply it to, the result may be longer render times....

I also got that product on a sale. I haven't tried it yet though.

Let's suppose I have a simple nightstand lamp. What's the difference in applying an Iray Real Lights magnesium lamp shader and using the Daz Studio 4.8 native Iray Emissive shader on the lamp bulb (and tweak the surface settings to emulate a magnesium lightbulb)?

I confess that I bought that product because of the neon lights that aren't easy to simulate with the Emissive shader.

Was wrong about magnesium, was mercury vapor, hd sodium and metal halide instead....

Nothing special about these shaders, if you find values for the different types or try it out yourself, it can all be done by yourself.
But even the iray emissive shader is just an iray uber shader with emission color settings other than "pure black".

Found it useful here that you get a big bundle of different presets to just click them in existing (in this case) ceiling spot textures...
And neon e.g. also seems to be nothing than a white "light temperature" with the matching emission color.