Wet or dry suit it doesnt matter.
I use both and have many of. Either way the wetsuits made by "surfing" companies have a lot to be desired and are often fashion over function.
By far my warmest suit is a made to measure titanium lined Elios Wetsuit two piece 7 mm
thats 14mm over the torso and as flexible as a "surfing" 3mm but needs a bit of care as the neoprene is less dense. They will do them in 9mm as well!! these are for hours in ice water.
Cons... pain in the ass to put on and take off and that is where the drysuit wins.
Just got a new Seac 7mm free like most of my suits
which should be good for this winter. If you want to keep using a wetsuit though you will have to move away from the traditional surfing suits. Drysuits, take your pick membrane or neoprene. if its neoprene mtm no boots membrane seals is the way to go and you will easily manage 8 hours on the water if its Heiwa/Yamamoto or Sheico. Fairly bulletproof too even flooded. Membrane suits...they are OK and I have a few but have a few too many issues in my view if the water is seriously cold.
I can`t wait to move to the tropics!!!