Note that Shawn, and any surveyor in the area, also does a lot of work (i.e., their bread and butter) for RCR, so they generally have to survey / stick with the letter of the law for surveys. They can't/ won't reveal anything not "on the list".
That's why it's great to be there during the survey- and you'll learn a lot.
Also, note that surveyors can't disassemble anything, not even a screw. So anything "hidden" that they can't see can't be surveyed. If the boat is older and/or you suspect that it has hidden issues, one could (ahem) get aboard ahead of the survey and do some personal disassembly, then later re-assembly. Brokers won't like it, so it has to be discreet.
Also, any contract should include an engine survey.
(1) contracts, RCR and others, typically aren't written to give you an out if the engine is really bad; rather they give you a lowball holdback ($1500) that won't cover a bad engine. Not to say that if the engine isn't shot RCR wouldn't let you out anyway.
(2) RCR has a spectacular diesel mechanic in Buffalo. This of course is done in the water, at time of handoff. Have him do a survey / inspection of the engine- not just to know what's wrong, but he is so full of info I wish he could be turned into a book.