If you want to dive wet in water that cold you need an M&B wetsuit out of long beach. I dive on the North Coast and we have water that cold more often than Monterey gets a cold hit.
I learned from the commercial urchin divers about what type of wetsuit works best for ice cold water. They will work 4 to 6 hours a day in water 44 to 46 degrees. They don't go home and cry to mommy when it gets cold. They order suits from 9 mil up to 13 mil.
I ordered a 1/2" two piece beaver tail which has an attached hood and 3/4 zip up the front. I've had the suit down in 44 degree water and didn't feel a thing on my body. My hands and face froze but diving in that suit is like diving in a hot tub.
I tried a drysuit for a while and I didn't like it.
Even though I paid about $1000 for my 1/2" M&B, I still think it's a better value then a drysuit. Spending $2500 for a decent drysuit not including underwear is not in my budget, especially when the cost doesn't stop there when you include replaced zippers, seals, pinhole leaks, and missed dives because of issues.
