What about the obvious drawback? It looked so stupid when I tried it with Eternity.
That was Muelsa's code, this is my code. Is it better than his? I have no idea, because I haven't tried his. It may be better, it may be worse, it may be about the same. All I can tell you is it didn't look too bad with Overkill, and the boost to frame rate made it worthwhile for me.
I suppose there is a certain performance threshold that your computer must reach for this approach to be worthwhile. I mean, if every light in the map has to be turned off before the target frame rate is reached, then you might as well play using Polymost. In my case, nearby lights were able to stay on most of the time.