Google Analytics Funnel Visualization Issue

Google Analytics has a visually appealing Funnel Visualization feature which is very useful for ecommerce applications and web systems especially for an ecommerce accounting system. It is much more visually appealing than Yahoo Web Analytics Scenario analysis feature.  But as we dig deeper into this tool we keep finding more and more problems. The latest problem we found is that when the rules of the Goal definitions are changed they dont operate on historical data but on new data only and that too after couple of hours. There is no way around this problem. Also as Avinash says: " if you set up a funnel today and a month later you remove a step, or add a step, then that change is only going forward. It is important to make a note of it." This basically makes this feature of the tool unusable for most realistic scnearios.