Salt water time versus fresh water time is something to consider in the survey or not question. Also, stored on land or on the water, and if on land, in hard covered storage or open to the weather. Used in dry parts of the U.S. or rainy and wet. If a boat is low hours and stored out of the water, a long history of fresh water useage, and in hard cover storage, there is much less need to worry about a survey. I've owned a dozen salt water and fresh water boats, and the salt water boats all had hidden problems that I didn't find until after I'd bought them. Two of those boats had been surveyed, but the surveys missed some minor, but still, costly points that were associated with the extensive salt water use. Not so with the fresh water boats.
Also, ask the seller to provide a warranty to cover the first few hours on the water. Agree with the seller to put some money into escrow until you've put it on the water yourself. A test drive is not going to tell you much about the real issues with a boat. Your need to have a day on the water, and when it is a cruiser, you need a night on the water. If problems are found that need fixing, then you tap the escrow money. Then the balance of the escrow gets released to the seller.
Of course, you are buying a used boat and there is always some risk, and a smart seller won't give you a long and open ended warranty or money back warranty and the buyer shouldn't expect that. There are also potential problems that can show up in a used boat that the seller wasn't aware of. That is the used versus new conundrum.
I've watched a lot of boats bought and sold on this forum in the last five years, and without exception, as far as I can tell, the transactions have been good events and I think, the vast majority didn't entail surveys. In one or two cases where a problem occurred, amicable solutions were worked out.
Bottom line is that the C-dory is a simple boat. You can pretty much see with your own eyes any problems other than core water intrusion. Water intrusion is a result of weather and water exposure over a long period of time and improper on or off water storage. A simple, short term guarantee from the seller on the engines and electronic systems removes that worry.
I personally wouldn't worry about buying a C-dory from anyone who's active on the forum with or without a survey.
I would be concerned and carefully consider any major, owner executed, modifications to the boat. Over powered motor for example or significant fiberglass work.
I sold my 32 foot Gulf Motor sailor years ago to a nervous buyer without a survey and gave him a healthy guarantee for 30 days. I was able to give him the guarantee because I knew the boat, and knew what true condition it was in. The only problem I had to follow up on was that the diesel anti-bio treatment I was using wasn't working. He lost engine due to plugged fuel filter a mile from the entrance to Marina Del Rey. He had to get a tow. I paid for the tow and for servicing the diesel fuel.
If I was buying a C-dory I'd ask for a very short term warranty from the seller for engine and electronics. If the seller said no, then that would be a red flag but not necessarily a deal killer. Once, I had an asking price on another boat that the buyer agreed to. He didn't ask, but I gave him back 1000 bucks and said that was my warranty on the boat. I simply can't stand the idea of selling something and having the buyer unhappy.
C-Brats are an odd lot. None of us can stand the idea of an unhappy buyer.