I am curious. Have you actually noticed a problem due to mismatched weight from side to side? If so under what circumstances? Heavy load? Light load? How imbalanced?

I ask because I never have notice any at all. I often read where folks advise taking care to balance the load and I do typically try to balance the load by not putting all the heavy stuff in one side. That said I have often had an extra liter or even two of water on one side and never seen a problem. My companions had 50 ounces of water in a camelback bladder in one front pannier and often emptied it during the day. They never mentioned any handling issue when doing so.

I have gone as far as using a pannier on one side in the front when just riding for the day and didn't find it problematic. I probably never had much more than 5 pounds in it though.

My experience makes me wonder if everyone just assumes that they never had a problem because they were always careful with balance when loading.