Here's the breakdown of why pervasive economy isn't as godly as it might sound. Let's say your opponent earns 100 credits per second, but suffers 50% upkeep. He has 50 credits per second to spend. Suppose 30% of that goes to techs and the black market. That leaves 35 credits per second for spending. Of that, you earn 20% from maxed out pervasive economy. That works out to... 7 credits per second on average. Needless to say, if you're running 8 labs and have maxed out the trade tech path as TEC, this should already be pocket change for you. This is why it's easy to think pervasive economy does nothing.
As I said, I do not recommend this in a 1v1; your opponent needs to have a massive income for it to ever be worthwhile over just investing this directly into trade or military firepower, and generally speaking if a TEC player allows an Advent or Vasari opponent to get this far in a 1v1, he's already lost. However, in a team game, this tech shines beautifully, and can really turn a game around.
