I just went through this process on for my much smaller Contessa 26; The Contessa is a very simple boat and I still felt it was necessary to get out and test the systems.
Having said that, here's what I learned...
1. Find someone skilled to do the sea trial with you.
I hired someone who turned out to not live up to their resume. This has resulted in a few unexpected surprises that I found on my 6-week shakedown cruise.
Best of luck,
See, this just pisses me off about surveyors. The whole purpose of hiring one, is so that you have an "expert" to find things that you, the "amatuer" would not find.
So you pay for an expert, and end up finding a bunch of system failures that he missed, that are blatanly obvious to you, the amatuer. I'm sure the same thing happens with so-called "home inspectors" when you buy a home, but still...
My recent purchase budget was only $4,000-$9000 so I did a bunch of research on Pearsons, research on general sailboat systems, Atomic-4's, various diesel engines, seacocks, through-hulls etc, and went shopping.
When I would find a likely candidate, I'd bring even more experienced friends with me to check it out to make sure I wasn't looking at the boat emotionally, with "rose tinted glasses".
This worked well, and I've had no surprises. If I was spending more, or looking at more complex boats, I definitely would have hired a surveyor and done sea trials, but I would have shopped several different surveyors, and asked for a lot of references to make sure I got a good one instead of a shyster.