I have an configurable product for example T-Shirts in size small, medium and large. And all have same price and we have tier price like: Buy 10 for 5.50 and save 10% Buy 20 for 5.00 and save 20%
Now a customer buys 5 medium T-Shirts and 10 large. So he has total 15 articles of this T-Shirt. Default Magento is now only take tier price of 10 large T-Shirts, but not for 5 medium T-Shirts.
It would be really nice to have option for product to set "use total amount of child products for tier price".