When you see me post in this thread you can guess which fins I'm going to recommend. But I'll back up my opinion with information that should make sense to a person with not much experience in carbon fins.
For those who may not know, I'm the owner of Speardiver brand gear, manufacturer of Speardiver carbon fin blades.
I've used the following carbon blades and foot pockets in different combinations:
Pathos foot pockets
Beuchat foot pockets
Speardiver carbon blades
Deep Apnea carbon blades
I have not used Moana carbon blades. My comments on them are based on the blade action I see in the Moana promotional video, other diver's reviews that confirmed my observations, and my experience with the carbon fabric used by Moana.
First the foot pockets.
Pathos
After my extensive experience with Pathos foot pockets (I was the first to bring them to the US and make them available through FreediveStore.com starting in 2009) I've come to the conclusion that they're not good foot pockets. The Pathos foot pockets are light because they're made of synthetic rubber, and there's significantly less material in them than with other more robust foot pockets. Consequently the Pathos foot pocket tendons do not offer enough support for carbon blades. The fin ends up flexing too much in the area immediately past the foot pocket toe plate, resulting in less power/propulsion, and at worst (too often) carbon blades breaking at that spot.
It appears that with Pathos' minimum material design, it's impossible to find a middle ground where the foot pocket tendons have the stiffness to offer the carbon blade adequate support, but remain flexible so as to not negatively affect the blade flex pattern (more mass/material is needed to achieve this).
I'll attempt to describe what it feels like using carbon blades with Pathos foot pockets. If the carbon blades are medium stiffness, as long as the fin stroke can be light, like in flat water no current conditions, or going up and down with not much weight on, the fin will perform fine. But the moment you need to power up, such as when fighting a big fish, going against current, or simply trying to go faster, the fins are immediately overpowered and you feel like you're kicking but not advancing.
If to compensate for this you switch to a blade that on its own is stiff enough to not be overpowered, you'll feel more pressure on the top of your foot about 2" up from the toes. It's as if the foot pocket is too small to dissipate the force of the fin stroke over your entire foot, and the blade has too much leverage on the foot resulting in fatigue.
Some new carbon fin blades manufacturers continue to opt for the least amount of work assembling fins (with Pathos foot pockets the blades are easily glued right in and don't require rails to be installed on the blade), and the easy sell aspect of the Pathos foot pockets, divers seeing a such a light fin for the first time are quickly impressed into buying it. Carbon blades are lighter than fiberglass and plastic, but the Pathos foot pockets are so much lighter than all other foot pockets, that's the difference in weight you perceive when you hold this fin in your hands. Some carbon fin blades manufacturers who don't have our experience, are not yet aware of the weakness with the Pathos foot pockets. Others who know of the problem try to address it by making their blades stiffer, this approach results in a cumbersome fin. Instead I choose to no longer recommend/offer the Pathos foot pockets, on their own or with carbon blades.
For those who insist on choosing Pathos, fit wise they are suitable for a wide foot, but are quite flat on the top, resulting in most of the pressure of the fin stroke being felt about 2" above the toes. Pathos foot pockets are not suitable for divers with a high instep, you will not get your foot in the pocket. Because of the material (or lack of) the Pathos foot pockets tend to split on the sides. This happens much quicker, 1 season of repetitive diving, if used in cold water.
Beuchat foot pockets
The Beuchat are nice foot pockets, they have moderate stiffness tendons for good blade support, a stiff sole for good power transfer to the blade, and a soft comfortable pocket. From my experience fitting divers, they are best suited for a narrow foot. This pretty much precludes anyone with an average shaped foot from getting them in the correct length. Meaning, to fit a normal foot you'll have to get a longer size Beuchat foot pocket, so your toes will end about 1" before the end of the toe plate. This changes where the pressure from the fin stroke will be felt to right above your toes, creating fatigue.
The Beuchat foot pockets are very difficult to install blades into. The T slot inside the tendons is extremely small, and there are no pre-made rails that will fit it so conventional rubber blade rails must be reduced by hand until they fit inside the tendons. Additionally the tendon channels simply refuse to open to accept the rails. I've done this installation a few times and it's a serious PITA. I therefor must charge an additional fee for installing any blades in Beuchat foot pockets. I highly doubt Moana and for sure not Sleep Apnea will be able to do it. The plastic like material of the Beuchat foot pocket tendons is slippery and Cyanoacrylate glue does not bond to it carbon blades, so it's impossible to glue the blades in properly.
and good fish too.
