
Might be true in very cold water temps, 40 to low 30's where you should have thick rubber on anyways but I use a 3/2 SGX with a hooded vest undeneath all winter in the southeast area till the water gets 40 or below. If you have a good suit it can handle colder temps than the manufactuers guide recommends. I have no extra restriction from the layering.
good sealed 4/3 and a bladder full of coffee oughta do it this time of year