Lighter. (ummmm sorry had to say it)
Faster to point.
Easier to steady off hand.
More mass soaks up all that heat. Will take longer to overheat. Will take longer to cool down. You'll be able to shoot more before your groups start to open up.
Stiffer, should be a little more accurate, depending on barrel length. (at 14-16 inches this really doesn't matter. But 20+ it makes a big difference)
I prefer LWs. I don't shoot full auto, and don't do mag dumps tho (well... not that oftern :P). I've taken carbine classes with LWs and they do just fine....I just don't get tired as quickly. 1 pound doesn't seem like a lot, but remember its all in the front of the gun. Having a LW barrel helps with the overall balance. For MY shooting style/intended use, LW suits me perfectly.