I've had the Equal-i-zer and the Hensley on the same camper/truck combo. I know with the 4 point, there was still some element of sway, but it was quickly controlled by the hitch. I still had a real firm sense the trailer was back there and kept an eye on it at all times in the mirrors.
Now, with the Hensley, I get a more "relaxed" driving experience. More of, one hand on the steering wheel like a "normal" drive. I still keep an eye on the mirrors every now and then, but don't feel the trailer as much.
Yes, you still feel the semis, just a bit, and one drive through Kansas was still very concerning (20-40mph crosswinds, with gusts). Awning were being ripped off campers on the road that day. We stopped at JJJ campgrounds and a Class-A, and a Class-C there both had the smaller slide awnings ripped off/ broken from the side winds.
As far as the engineering of the control of forces, there is only one point of contact on your vehicle, the hitch receiver. All forces have to go through that point. I installed a rear view camera to keep an eye on the Hensley the first trip out, and you do see the hitch head move around a bit, but that is not felt in the truck. With the equalizer, when it moved, you immediately felt it, hence the hands at 10/2 all the time. The orange head floats on a set of trapezoid pivots above the black part that goes into the vehicle. The two parts virtually project the pivot point
and forces forward in regards to the campers perspective. Same real point of contact on the truck.
This is only my perspective of what I've seen with actually using both types of hitches, and I'm just a country boy living in the city now.
I've read a bunch of these types of threads, and most take the same direction this one has. There will be strong opinions put forward, but I've yet to see a posting on a thread of someone who has used both say they prefer the conventional type over the Hensley/3P type.
I found one 3P user had experienced hitch head failure due to poor welds on the stinger. Poor, non penetrating welds would have probably failed on any hitch head. Hensley won't make an adjustable hitch head for their brand, but thousands of 3P users, with the one exception I found, are safely using them every time they tow. And FYI, shortly after getting my first camper, I found one thread on an equalizer that failed at the bracket/sway control points as well. I actually carried an extra bracket with me after I found that.
Honestly, I think we all reach a point where we are comfortable with our vehicle/hitch/camper setup. I don't think, my opinion only from what I've read/researched, the Hensley/3P will damage our vehicle any more than a conventional hitch. Yeah, I could use a Freightliner to tow a popup, but I got's what I got's and am good with it, myself.
Heading off to slip on a pair of asbestos undies.....