It appears that all of the reviews in the thread you linked are for the older model Essence. I have the newer blue model with the two long side zippers.
In my experience, how you pack up your gear makes a huge difference in how the essence handles weight. The Essence is the only pack where I put the heaviest items at the bottom, near the waist. Since I use the long padded hipbelt, I am able to secure the bottom of the pack to my hips.
For me this means my inflatable pad goes in the bottom, followed by food (which puts it next to the opening).
My next trick is to put my sleeping bag and insulating clothing in 2 large tube-shaped stuffsacks that I insert vertically (kind of like 2 AA batteries in a Garmin GPS unit). Since the pack is rectangular, These vertical stuffsacks provide the structure in the backpack that keeps it from collapsing onto my shoulders. Top pouch has light accessories.
Lastly, keep in mind that I had 23 lbs of supplies, which is on the high end but not unreasonable for a frameless pack.
Incidentally I also own a SMD Starlite with the aluminum stays, and by packing the Essence this way, I find the Essence at least as comfortable as the Starlite. I keep the Starlite around for my wife and for trips with bear canisters.
Here are some examples. One of the things I like about the tubular stuff sacks (from my GoLite Hex 3 tarp and nest) is that it really removes the pressure on the zippers, sine the sacks themselves absorb the compression strain.
This pack holds more than it seems: In the orange sack is a GoLite Ultra 20 quilt. The Black sack has a Cocoon pullover, cocoon pants, and cocoon pro balaclava. Both sacks are only loosely compressed. I've also got a Tarptent Rainbow and poles in the left pouch, an ID eVent Thruhiker rain jacket in the top right pouch (orange), a BA insulated air core in the very bottom (not visible), an Ursack (the green bag at the bottom opening), and my cooking kit (Caldera Cone) in the small conical sack sitting on top of the other sacks. Since the back panel is flared, the cooking kit fits there perfectly). I also usually have a GG nighlight folded in 6ths strapped to the back (under the two straps), which makes for easy removal at rest stops and protects the back of the pack (and the somewhat exposed caldera cone). I also use a GG SitLite pad in the main pad pouch; it makes everything feel flat against my back. In the last photo, you can see how close to my back everything is.