I've got a pair of Panaracer RiBMos. Panaracer lists the weight at 370 grams. I haven't had them on a scale, but they don't seem heavy.

I rode them around at about max pressure (120 psi) for about four months, but lately I've gotten lazy about topping them off and I'm finding that I like the ride a lot better at whatever pressure they're at now (possibly around 80 psi) -- very comfortable.

They don't feel as fast as the Gatorskins that I had on the same bike before I got these, but the puncture resistance is better. I had one flat with a nasty construction staple after about 100 miles, but no more flats in 1500 miles since.