Vest, inside or out?

[blue steal]

I'm not quite sure how a hooded vest could keep you as warm if worn on the outside. There would be two large area around the opening where your arms go and this would let water in between your vest and full suit. If worn on the inside, very little water would enter the full suit and the thickness of the vest/fullsuit would keep you warm.
I am asking because I have just purchased a 5mm hooded vest myself and have not yet tried it out yet.
Heck I'm thinking of wearing my regular 3mm hood over my 5mm hooded vest to get 8mm protection for my head.

 

[DiveMaven]

To my mind the best way to stay warm is not only wear enough neoprene, but also to eliminate (as much as possible) water movement inside the neoprene. To do this, you want a solid barrier with the fewest entry points as possible in your suit. The best way to accomplish this when layering a vest, is to put the vest on the inside so your full suit is a solid barrier on the outside.

 

[oldnotdead]

I don't have many dives with the need, but I use the hooded vest outside. The neck seal stays intact in case I need to adjust the face seal. The vest helps seal the zipper on the wetsuit.