I have a "light" alpine climbing set up for scrambling with short sections of class 5. Biggest savings is that we take a short rope (about 80 feet). I also have the smallest carabiners and use mostly stoppers with only a few Aliens. I also use the very thin light spectra slings. My usual alpine climbing partner is another gal and neither of us weighs much, so we feel OK about the light gear. Bigger guys have refused to climb with our gear! I also have an 8oz helmet and use a light harness - the ones that are used in indoor gyms. I do approaches in light tennies (1# 4 oz) and have comfortable enough climbing shoes to put them on early if the approach gets harder.

For serious alpine climbs - mostly class 5, we use twin ropes. This is mainly for the ability to do a full length rappel when lighting threatens. We still use the light biners and mostly small cams and stoppers. And of course, the amount of protection is about doubled.

Years ago I climbed Moon Goddesss on Temple Crag (about 12 pitches, 5.8) with an eastern European. We did the entire climb with 8 cams and 8 biners and one rope! Half way up the rope was cut in half by rockfall. He lead and took absolutely NO exra clothing or food; I cleaned and carried a pack with food and extra gear. He did indulge in my extra food! When he ran out of gear he would salvage used webbing and tie it around a rock and jam the rock in a crack! He was not the least worried. I asked, and he said, in eastern europe, nobody uses gear; you fall, you die. He had no intention of falling. So I guess the lightest gear is your guts.