As far as the hard engagement, try this. Be in a good area, try to engage them. If they hit that hard spot, back off and rock the truck slightly. My really old Warns, were direct engagement. If the splines inside the hub were not lined up, they would not engage. So, if you were stuck, you would put my Jeep in gear, move it slightly and try again.
Then Warn started putting springs between the spline block and the knob. If the splines were not aligned, the springs would compress and let the knob turn all the way.
Then, when you moved, and the splines aligned, the springs would engage the hub. Back in the day, I never liked that, after having pulled a friend out when the grease in his hub was too gunky to let the springs do their job. Mine were a huge pain in the butt, but when the knob said engaged, they were darn well engaged.
The hubs you are using now, are the same as I put on my Ford the other day. Instead of the wimpy little coil springs, they use some wavy washer type springs that get pretty darn strong when they compress.
That last hard 1/4 you are feeling is the springs compressing. If you get the splines aligned, they engage easily all the way. You could also engage them, roll the wheels a short distance to make sure they are engaged.
Then stop the truck, disengage the hubs, then try engaging them again without anything having moved. If nothing moved, the splines should still be lined up and the hubs should go in easy.