Personally I found the whole stealth enhancer tree to be useless. There's no need to see how much noise you're making, because even when I deliberately tried to lure guards my way by making all sorts of racket, I had a hard time. Also I never upgraded the stealth cones augmentation, since the enemies are already almost blind and there really are no positions where you can't get around them. That might be because later in the game I used cloak to great success, even approaching foes head on to do a double K.O. And finally I disagree with Gamespot that the typhoon is useless to a stealth char, because only for a 3 praxis points total you can kill bosses with much more ease, making the life for a LTL char a lot easier. BTW I finished the whole game without killing anyone and had absolutely no problems on the highest difficulty without using the silent walk/run/land upgrades also.