I have the zen, so while not 100% relevant, I think close enough to weigh in on the recent comments.
I chose the aluminum Zen for the double-layered bladder and because if I want to, I could switch it to a doubles config one day, which wasn't an option with the ghost. They are incredibly similar, other than those differences and a slightly smaller, slightly different shaped backplate. I did not get the comfort straps (because of additional points of failure), but did order the medium size weight pockets, utility pocket, and trim pcokets with the Zen. I've never used the trim pockets since I generally leave them at home and if in the rare instance I need extra weight, I just run the cam band through one.
I love my zen!!!! I have to travel to dive, and it's gone everywhere with me from the mid-Atlantic since I got it. Roatan/Utilla, Maldives (multiple islands), Hawaii, Cozumel, Tulum, Isla Mujeres. My reg bag goes in my backpack usually, with my spare parts and tools etc in my checked bag. My BCD, fins, masks, boots, flip-flops, swimming trunks, and maybe a few other small things all fit in my size large (75L) Marmot Long Hauler duffle, which I carry on. It can get a little heavy after a while but I'll deal in order to make sure my dive gear doesn't get delayed. Recently purchased an osprey transporter 120 that gives even more room. On the return trip, i usually check it and pack it all in the transporter with other stuff, so I'm taking less weight in my carry-on.
Now that I'm almost 50, the travel setup may change a bit but I still prefer to carry it on at the start my trip since I'm usually diving that night or the next morning and the thought of not having my gear doesn't sit well with me.
I've had it since spring of 2022 and have about 90 dives on it. I was certified on a Zeos dive center edition (rented at the dive center) in December 2021 and rented a Halcyon (from my home area) for a trip to the DR before the Zen arrived, totalling about 50 dives. My point being, other than my pool work, I've never used a traditional BCD, and now you know MY frame of reference/perspective.
The Zen was definitely lighter to travel with than the Halcyon. How it compares to the Ghost, no idea but that's in the specs.
Regarding the placement of the D ring on the left side for the SPG. It does seem a little far back and was initially fiddly to reclip, but I actually like that it's back, tight against me, and out of the way while diving. I rarely use it anyway since I have air integration with my Teric and Perdix. Side note, getting a bolt snap like the X-Deep NX large series with the large back ring makes it a lot easier to reclip.
As far as the weight pockets go, like I said above, I originally ordered the medium-size weight pockets. I dive with 6 to 8lb with an 80L and no weight with a 100L+. The medium weight pockets were overly large for a 4-lb weight, and I think there was once where it partially slipped out. But in order to reduce travel weight, overall size, and drag underwater, I ended up buying small weight pockets and attaching those and it's perfect for the amount of weight I dive with. I've never had to dump them, so I can't comment on emergency situations, but I don't see it being all that complicated. I've added or removed additional weight from the pockets underwater sever times, and the challenge is getting them back in and reclipped where you have no visual reference. Unclipping has never been a problem though.
After having a mask issue underwater once, I always dive with a spare mask so I do use the utility pockets and also keep a folding dive knife in there. I also use it to stash any trash I pick up while diving that fits.
Hope my perspective was helpful!
