At what ratio should soluble and insoluble fibers be eaten?

Varies: This depends on what you are trying to achieve. In general insoluble fiber is taken to bulk and hopefully soften your stool if a tendency to get constipated is the reason you take it. There is no real therapeutic role for soluble fiber that I know of even though it can't hurt. It is assumed that the carb is less rapidly absorbed leading to a lower blood glucose level.