Though HOI is my least favorite series as far as Paradox's series go, I like their research system. I know it's obviously too late to change for Vicky 2; but I'd hope that, in the future, you allow for research in all games to be similar. I like the idea of being able to chose a national focus, rather than the generic "1, 2, 3, 4" system. In an epic game such as Vicky and EU, research like this could be a HUGE difference. Think about, for example, if the French took a route focusing on ships (ironclads, early subs, etc.) and the British decided to focus on different types of rifles, cannons, etc. When the Napoleonic Wars came, the French may not have the sheer numbers that the British Navy would have, but maybe their tech could help them keep the British at bay.