first thing i noticed is the enemy response patterns have changed slightly for the better. you can still wipe out half a platoon from long-range using predator bow, but if you're not strategic about who you snipe, or even worse you miss, it looks like they're a little more dedicated when it comes to searching for you.
by the time i got to level 40 in the original game, i could walk up to any enemy camp and immediately determine who it was safe to snipe, and who i would need to get up close and poison before making my way inside to get my hands dirty. and the way i play, once i'm in i'm murdering everyone. lol, i dont play that solid snake, get in and get without being seen bullshyt, so i've literally left no survivors at every single enemy base the game has to offer. usually for me bases are only challenging because of how big they are.
i never would get caught sniping with the predator bow in the original game. even when i missed i would just let off another shot or reset my position and wait for shyt to calm down. well... i sniped a dude last night without triggering any alerts, and because one dude reacted and ran to the body after it happened, the enemy immediately sent 6 dudes in the general direction the arrow came from.
first dude walked up to the bale of hay i was hiding in (which was tucked behind 3 tents in a corner, next to a ramp... it wasn't out in the open), then moved on. 4 other dudes walked around me. and right when i thought i was safe the first dude came back after finishing his sweep, poked the bale of hay, forcing me to kill him in front of the sixth dude, who immediately ran up a ladder and lit the reinforcements torch (the whole reason i was in that part of the camp to begin with). i actually beat him up the ladder, but stood too close to the ledge trying to knock him off the ladder and missed, allowing him to light the torch.
that was literally the first time since i was at level 20 that i got caught creeping through a base. and it definitely felt like it was because the enemy was using new tricks to track me.
they also staggered the layout of the base in a way that makes you get closer in order to deal with some enemies. the base i raided was partially in water, partially on the main road, partially underground, with one major camp near the first road and a second major camp built into two rising levels of a big ass mountain that led to a path into a new region...
SPOILER ALERT:
AND A NEW PHYLAKE