In my car I have a turbosmart dual stage boost controller setup and I experimented by removing the blockage to the stock 3SGTE boost controller (T-VSV) to see why its so necessary.
Basically now there are 2 bleed valves hooked up on one system I have no boost control in 3rd gear or above.
When im in 3rd gear and I punch it (carefully watching the gauge so as not to overboost) It spools up a faster, getting to boost pressure noticably quicker than when I just have the turbosmart hooked up. Im not too sure about the way this BC is designed, but im assuming its not gated which would explain the 'lag' for the want of a better word.
IMO EBC is the way to go...as i have an S-AFC already I would lean towards the apexi, but also because it has a lot of features i like i.e. injector duty % and so on.