Honestly speaking, your team has the right idea. When it comes to invading nests, Night Hunters have a HUGE advantage to the extent that while the night hunter doesn't have any resistance against high-powered weaponry, it's minions DO. Forty seconds of whacking a single zombie and getting pounced versus dropping one of Zaid's flares, keeping said infected at bay, and preventing a potential pounce without a spit warnings, and probably killing a nest.....I'd much rather drop the flare. The only other alternatives are to try and gang up and swarm the night infected surrounding nests, but that makes you a pretty big spit target, or you could also try luring away some of them and running for your life, but that's asking to lose a life is there's a night hunter around. As for them being super-strong, I'd rather say extremely durable. They're more a hindrance, but can burst damage if they swarm around you - Hence flare. A quick tackle and execution COULD deal with them, but frankly, it isn't worth the time if you can knock out a nest in a minute and grapple-hook your way out or sound off a trap, and already be gone before the night infected know who to run after.
That really isn't the kicker. Besides things taking a few extra swings to kill something, if you newgame+ it, it really isn't that much difficult at all if you did what I did and just ransacked every crate and police van and shoved into your duffel bag of holding. The REAL kicker is when you're up against those scripted scenes - I.E. Those escapes where you're getting shot at, or have your weapons taken from you, ESPECIALLY in Rais' arena, where their idea of evening the odds against an improved demolisher is to give you a 67dam hammer. I'm not passing that level any time soon, or if I am, it'll be with the aid of 3 clones of myself ganging on this thing. Overall standard gameplay hasn't really changed from normal to hard, and if you're doing NG+ then the difference is negligible - Up until those points where you're thrown against the odds via scripted story mission, and Techland didn't scale the items correctly to balance it out. Giving things more HP can calling it hard isn't always the way to go. I also felt that they should've increased firearm damage if they were gonna make scavenging for ammunition more difficult to actually make finding and using guns rewarding. I kid you not, one of Rais' thugs took about 15-19 shots to center of mass before he keeled over and died. Granted it was the military AR, but you get the point.