Upper-back/shoulder soreness are my largest complaints about my Titan. I'll be in the market for a new chair once I feel like I've gotten the $500 I wasted on this POS out of it. Probably in the next year or so.
At 6'0'' and 188lbs., it sounds like the Gesture is probably best? I don't care too much about the seat, since I think the Titan seat is uncomfy as fuck and it doesn't really bother my lower back.
The lumbar of the Embody is in the base of my buttcheeks nearly, then fades away from my actual lumbar as you go up the backrest. By the time you get to lower-mid lumbar region, it evaporates if you prefer sitting up straight. You can slouch out and bend concave with the Embody and feel the mid-back, but this is pretty unhealthy. The whole point is to sit straight. It's also way more slouching than I would normally do, even if I wanted to. It's not a good slouch to make contact with that mid-backrest area. However the lumbar is not hard, and can't cause soreness and doesn't put any force on the tailbone itself.
You can remove some of the concave bend with an adjustment knob to release the 2 prongs on the top of the chair to try to get more contact with the mid-back.
The problem with releasing the top prongs of the backrest is, you just lean away from your entire desk. The only viable sitting position is to keep the prong points forward. This prong region is annoying at first, but it's fully flexible and can't poke or cause any pain. It bends even when fully tightened. You could get used to it if you keep good abs and you yourself do the work and sit up straight on your own. You sit driving your upper back into the top of the backrest and maintain some weak abdominal tension. I'd remain skeptical that a 6'0 person would be able to comfortably make contact with the mid-back without concave slouching out. If you were 5'10 I'd say give the Embody a shot for the seat sake.
I found myself sitting with my ass and my entire lower-mid back off of the Embody, just leaning my upper back into the top prongs only. This is unsustainable for anyone just trying to sit down because it requires you keeping slight ab tension and also proactively driving yourself into the prongs for support.
You can get used to doing the work to sit a certain way in the Embody as a taller guy, but it's learned behavior.
That's the biggest contrast to the Gesture. The Gesture contrast is, you don't need to sit up straight on your own. You sit down and it's done. You never adjust your back in the Gesture.
The Embody is still the best seat for circulation and overall seat comfort on the market. Nothing else even comes close to the Embody seat. The only reason you can even fight with the backrest of the Embody and do all this work and shifting around is because the seat can handle pressure and micro movement in position from any angle and the whole thing is a spring loaded cloud basically. From the back of the seat to the front of the seat there is 0 dropoff in the function of the seat design. Everything has bounce and spring on it. And it's wide as fuck, wider than the Gesture. If you like moving your legs side to side, or like shifting around at all, the Embody seat is the best seat for that. It's a real shame the backrest is atrocious.
More on the seat: the Embody sync fabric won't catch on skin at all. It's more similar to silk. The Gesture will. Can you wear shorts or boxers in the Gesture? Sure, and I did that. But your skin is going to feel it and you can't shift around your legs like you would in the Embody. The Gesture fabric is textured enough to be able to "grab" cloth also. So it'll slightly grab clothing, helping you stay in place, but also catching you sometimes. But at 180lbs, I'd say this is no concern. Catching is a problem the heavier you are. But I'll say it again, if overall seat comfort is a big deal for you, and you don't mind taking some risks with the fit of the backrest, or fighting your backrest daily, try the Embody. 6'0 is really rolling the dice though.
But that's what I mean when I say these are polarizing chairs. The seat and backrest are polar opposites and not even 50% of effectiveness between them. It really felt like 0% or 100% tradeoffs. It wasn't like Oh yeah, the Gesture seat is 50% as good as Embody. It's not. It's a foam seat. It's sittable and I didn't bottom out in it like I did with the Leap. It's fine. I wasn't sitting on metal. At your measurements you'll have 0 problem with the Gesture seat or backrest. Just beware of the fabric thing if this is for home use only and you aren't a guy that wears pants all the time. If you are used to Titan fabric, that's more like Embody fabric. Gesture is more like office chair fabric, durable with longevity.
If you are looking to go to war with a chair to win a seat at the expense of your spinal column and neck possibly, then you go Embody. If you just want to sit down and forget it, or you have any concerns about back problems at all, it's the Gesture.
Someone on reddit said the Embody is "it's like fighting me". And I'd agree with that. It keeps you active, it keeps you moving and fighting-- for better or worse. But you have absolutely no mid-back support, the lumbar is atrociously placed. For big sessions thats completely unsustainable. I can't see anyone enjoying that past 2 weeks, even if the seat is PFP champ.