Interesting thread, Mark. I think I agree with everything you say. I have read surveys in the purchase process and then did a walk-through and found things the surveyor missed. I also have looked at more than one survey on the same boat - and they got lots of things wrong, like displacement, boat length, tankage, etc... On a survey of my boat, they surveyor mistook the TV antenna half way up the mast for an EPIRB!
So... I think an experienced mariner who has really torn apart a boat and rebuilt it would probably armed with a moisture meter might do just as well or better.
I had also paid surveyors who were illiterate. All in all, I won't use one again - then again, I won't need to, but the point is valid. No offense to surveyors or their business - but it seems as though they might be best for people with less experience in some cases. It's a valuable service they provide and it's quite essential in many cases (espcecially if you get a loan).
But... if you're paying cash and you're used to boats - seems like doing it yourself is the way to go.