Was asked about how I had this set up and figured I'd do a post since when I was looking there wasn't a ton of info. I want to start off by  saying the ergo isn't going to be for everyone or even most people. It fits my narrow use case and I'll detail why in case it fits yours.

First a few disclaimers keeping in mind I'm still making adjustments and I think it will take anyone using one quite a while to get it dialed in right.

1. My primary reason for using this is as a safety device. I have quite a bit of arch to my back and the bottom edge of my plate rests in an awkward area. It took one time dropping prone with 3l water on my back to decide that wasn't going to work not to mention if i fell back hard. The ergo spans the contact down to my lower back/hip bone area eliminating this issue. It has some other benefits and drawbacks but this is the reason why I wear it.

2. The ergo fits my height and curvature well. If it doesn't fit yours you'll probably hate it. Imo to be widely accepted they would need to offer different lengths and ideally custom fit the curvature to the individual like stays in a pack can be customized.

3. It creates standoff. This can be controlled by the tension adjustment and with the tension let out it lays pretty flat. Unfortunately when you're wearing a pack when you'd want it laying the flattest is when you're going to want the tension cranked up to lift the load and aid breathing.

4. This leads to use case. Imo if you're going inside buildings, doing urban fuckery, or general cqb this probably isn't for you. Especially with a pack or even a heavy bladder it significantly increases your turning radius and will hold you off trying to hug a wall. Living in the woods it's not really a concern for me as I'm much more concerned with width vs length since being narrow allows me the worm through the brush. It does make going under things more difficult but there's no free lunch.

The positives other than the safety factor.

1. Load lifting. It acts somewhat like a frame pack and takes some of the weight off your shoulders. You can also arch your back and hike the load forward if your rear bag is sagging without using your hands. Similarly at rest you can arch your back and take the load off your shoulders to give your shoulders a break without taking your carrier off.

2. It aids breathing. This feature at least for me works as advertised. Crawling up a nasty creek bed I got stupid and almost fell a considerable distance onto some rocks. After flailing and recovering I was borderline hyperventilating and my ocd calmly informed that the ergo really helped with said hyperventilating. Additionally this allows me to run my bund tighter than normally would. This is good because on wet gortex the lower back pad can be a little slippy slidy and the tighter bund counteracts this.

Current setup. I've only had the current setup for a couple hikes. It was comfy for a five mile but did a 10 mile yesterday and my shoulders were hurting by the end and are a little sore today. To be fare I've been slumming with a belt kit for most of the last year or wearing a light pack so my shoulders aren't exactly in shape. Shaking this out for me also involves rectifying that as well so cause and effect is a little difficult to determine until I address that.

In the current configuration I hiked the plate up higher and let a bit out of the shoulder straps on the carrier. Also one wrapped through all the available slots on the shoulders eliminating all slop between the ergo shoulders and the carrier shoulders. I think I like it this way but it's only been a couple hikes and it could be in the long run a little movement allowing things to settle where they want will be superior.

The black tabs on rear bag are one wrap stacked three deep. This keeps the ergo centered on the rear bag. With a heavy load and the tension cranked up I found it had a tendency to tilt to one side or the other.

That's all I can think of for now and I'm happy to answer any ?s. Not trying to discourage anyone from trying one but imo it's a niche piece of kit that I'm a fan of but the drawbacks will be unacceptable to a lot of people.