You need to change your mindset somewhat. Instead of thinking about how to "push" materials around, think about how to "pull" them to the right place. If you, say, need to build one thing with 8 iron, and then one thing with 2 iron, you have Retriever at each table pull the exact right items. Or if you want to avoid blutricity, just trigger 5 transposers, and have 4 of them go to one place and 1 to the other.
The main thing is, redpower functions very much off of redpower signals (no big surprise). You can control the rate at which different parts of your factory run very easily simply by changing the speed at which things are triggered. If you go to low, things just run a little inefficiently slow, and if you go too high, you have a bunch of materials sitting in buffers, but it never overflows, and you can tune it to perfection.