Well, I heard that claim before, and did some research of my own. As for the Vitamins – although chickpeas are certainly rich of them when raw, you shouldn’t expect much of it to survive the long cooking. Much of the nutritional value attributed to hummus, actually comes from the tahini – as far as vitamins are concerned. The cooked chickpeas are still rich in minerals, though.
The soapy flavor thing is, indeed, a possible side-effect of baking soda overuse. The secret, naturally, is to use a small amount of it – which all good hummus places do, with great success. You CAN use a pressure cooker, as one of the readers suggested a while ago. But if you don’t have one the baking soda is a must, or else the chickpeas would never be soft enough to achieve that famous creamy texture.