Lets really try to figure out what is going on here. First of all, I am assuming we are talking only about fogging in the interior of the housings, not the exterior, which gets washed off. When the acrylic housing was fogging a lot more than the aluminum, were you going from air conditioning to the water? Were you SEALING the housings before leaving the air conditioned room? Were you ever taking your "naked" camera outside the cool/dry room? If I ever take my camera outside "naked" and then bring it inside without letting it "air out" in dry air with the lens off for a few hours, I can have a hell of a time with fogging inside the housing!!! Barring that, plastic housings will have more problems coming from a cold environment if they get opened outside even briefly or have a camera filled with humid air inserted. This is because the aluminum conducts heat MUCH better, so the interior wall of the housing reaches a temperature above the dew point temperature faster when exposed to the warm outside air, getting rid of condensation conditions. Whereas the wall of a cold acrylic housing stays cold for a LONG time. I had an Ikelite housing that I had to leave in the garage overnight if I was going to be opening it at the beach , because here in the humid Florida heat , it would fog for HOURS once I opened it if it was in the A/C overnight. This insulating property also keeps the air from getting warm in the housing, and is why the dome fogs more with the acrylic housing.
If you are starting with an aluminum and acrylic housing sitting open, outside in the nice warm humid air, and close them then plunge them into ice water, they will both eventually form condensation, the speed will really depend on the thermal conductivity of each part of the housing (in other words, as each part of the housing wall dips below the dew point temperature, it will start to fog). I would think that since aluminum is so conductive, that part of the housing would start to fog first (before the port). Where condensation forms first on the acrylic housing it would really depend on the thickness and thermal properties of the housing and port. If the ports of the aluminum and acrylic housings are the same in THIS circumstance, the acrylic housing PORT would not fog faster (unless it was VERY thin).
Between glass and acrylic ports, glass is much more thermally conductive. So coming from a cold room with bad dehumidification, or walking outside with the housing open, then glass will be better because it will warm up in the air faster. If throwing two warm humid ports in the cold water, both will eventually fog, but the glass will fog faster.
Really the easiest and only way to think about this is, condensate ONLY forms when air is brought below it's dew point temperature, which is determined by the partial pressure of the water vapor (Relative Humidity)in that quantity of air.This can occur when the air contacts a cooler surface, in which case the condensate will form on the surface.
(I really promise this is true cross my heart as a hyperbaric specialist and anesthesiologist - gas pressures are how I make my living, check my profile).
Now if you have
1.a really hot video camera warming the interior (keeping the interior surface above dew point temperature of the air), or
2.moisture munchers or a vacuum decreasing the partial pressure of water vapor in the housing (decreasing the dew point temperature of the air)
or a combination of the above, it will help prevent condensation.
Also, the reason why any water which might be trapped in moisture absorbent packs and absorbent plastics in the circuit boards you mentioned won't significantly contribute to increasing the partial pressure of water vapor in the vacuumed housing is twofold. 1. the material is hydrophilic by design, and is very slow to give up the absorbed water. 2. In the liquid form of water that could be drawn from these materials is somewhat trapped in the liquid form until you reach the activation energy to effect a phase shift from liquid to vapor (in layman's terms, evaporation is slow to happen in a cool environment). This is why you could put a paper cup full of water in your housing and it would not immediately fog, even though there are more than enough total water molecules in the housing to saturate even the hottest air.
The bottom line is if you are in a steady state with a cool/dry camera, and put it into a cool/dry housing then seal it, putting it in water warmer than the room can not make it fog unless the housing is leaking. Did you ever see a clear plastic housing after it springs a tiny leak at depth? If so, you might have noticed that if fills with condensation even if there is a tiny bit of water inside. That is because of the increased pressure causing the partial pressure of water to soar (opposite of the vacuum).
I think the most likely scenarios for your fogging issues you describe is that
1.the camera was brought to a higher humidity area (maybe the boat's salon?), in the hours preceding being placed in the housing. My wife had this problem with her Gopro because she was charging the batteries in the salon of a liveaboard which was very humid, then bringing the Gopro to the air conditioned cabin, where she was sealing it in the housing. It would fog up every time.
or
2.the housing was somehow opened partially after leaving the cool/dry
room.
Please let me know if this helps
Peace, Doug
