The new wheels weigh about a pound less than the old ones. 500 grams is the weight 17 ounces of water. Can you tell the difference on a climb if your bottle is full or mostly empty? It'll cut a couple of seconds off your climb, perhaps.
Light wheels that spin up quicker also spin down quicker, so the net effect is quite tiny. But they seem faster. My replacement wheels went from 2000 grams to 1550, and I noticed a quicker steering response. And they felt faster, but was that a real effect or just expectations?