I'm the author of the article you're talking about, The Time For Experience Points Has Come And Gone.
As noted, my gaming group has given up on XP in all our D&D* campaigns. It was introduced by one GM, but all the players immediately assented and starting using it in their campaigns (all but one of our players also GMs in one group or another).
By and large, this hasn't changed behavior all that much - players that like to kill things still kill things, especially if they think there may be loot. There's been a slight reduction in homicide in situations where there's a non-mission-oriented monster (especially one unlikely to have treasure, like animal intelligence ones) in a location, and it's made negotiating a truce more palatable to the kill-happy players. For example, we were going through some haunted castle thing and there were a good number of big animal-critters hiding out in the outbuildings we managed to convince our fellow players not to attack. "But... XP!" would have been an additional argument on their side prior to this change.
It has reduced time spent recordkeeping, and jealousy among players when one levels and another doesn't - as well as level disparity causing player experience to degrade or GM prep to be harder.
Also, since you can level as quickly or as slowly as you want, it allows for various play experiences. My Reavers campaign's been going 4 years and the players are level 8 - it has the benefits of being like E6 or E8 but without actually having to change any rules, just by slowing down advancement to the desired rate. Conversely, when we finish one thing and a GM wants to run a higher level adventure, we just advance. (Several APs don't have enough XP in a chapter to advance to needed level and want the GM to throw in some random grinding to get the players higher - bah to that). This led to improved player satisfaction, as even the more kill-happy players don't like pointless grinding.