it's fairly evident the Infected are much more aware of players and noise - it's nice to see them reacting to doors being opened (which was in patch notes some versions back, but didn't seem to really work back then).
I was able to sneak attack a fair number in broad daylight by crouch walking on grass with hiking boots, and even some other terrain - but they are definitely MUCH more aware than 1.24.
Our players are really only bothered by this because infected behavior is still janky as hell. - being hit from yards away, being hit when the infected isn't facing you, stuttering around (our server performance is excellent but yes this is desync), new warping through doors
I think if BI could get much better consistent behavior from Infected most of the complaints would subside.
As some of our players put it - I'm doing everything right and still being hit - it's frustrating.