The idea behind this is to (a) allow players who got into the lead and attracted too much unwanted attention to take the bullseye off their forehead, and (b) to give players that are being ganged up on a bit of an edge.
I think early on, this seemed about right. I know myself and a few others spent down to get an edge and to reduce aggro a bit.
However, late-game I felt less sure about how this was working. We had quite a lot of people who 'gave up' on winning because they were a fair bit behind the curve, so basically just spammed out specialists as often as possible using this. This resulted in a pretty strange game-state that I'm not totally sure was advantageous.
Initially, basically it was 5-6 players just spending down their entire Np balances trawling for Martyrs or other good nuisances and trying to cause general havoc while at the same time removing their chance to win. (This reminds me a bit of the land destruction arguments in Magic: The Gathering--where most players argue that land destruction is very un-fun unless it is part of your win condition or leads to a victory. Just using mass land destruction for the sake of setting the game back is usually very frowned upon.)
Two or three of the guys are commenting that they realized that spending down was probably a bad idea towards the end of the game, since it ultimately removed them from contention even though they actually had a bigger chance of winning than it appeared. In this way, unless it is used very carefully, it feels like a little bit of a trap for inexperienced players.
I'm not sure what the target is for late-game specialists density so I can't really say if that was good or bad--although I will say there were at least 30 specialists involved in a fight at the end within like a 2-3 node radius just from a couple players.
(Again, not really saying if this is good or bad. Just general feedback as to how our game played out.)