I find the difference between heavy and light strings to be a tonal trade-off, but I actually believe the lighter gauges have a slight edge. While heavier strings sound naturally thick, they often lack sustain and finesse. The lighter gauges provide smoother/more accurate bending, and the high harmonics are more extended and effortless. The only problem I have with light gauge strings is the way a heavy pick causes them to deflect more, making articulation a bit more demanding...
All of this assumes the player has made all the necessary playing-touch and tonal adjustments to maximize the effect of the particular string gauge they have settled on...
Having said this, I believe a great player can make *any* gauge of string sound heavenly, and I have seen numerous demonstrations at either extreme, light or heavy... Pick your Poison!