I only want to note that the amount of saidar used at the Cleansing was smaller because they weren't trying to use the full amount - they used a large amount to cleanse saidin, but their purpose wasn't to wield the entirety of saidar at one time - that would have exhausted Nynaeve too quickly. When Rand channeled saidar through the Link, he sensed that it was almost as large as saidin but powerful in a different way.