Make sure your ins co or bank will accept the surveyors report before hiring them. I learned the hard way and it cost me $750. Surveyor said yeah no problem I work with that bank all the time, bank said no way he's not SAMS or NAMS. The first question I would ask a recommended surveyor is what their accreditation is, then confirm the bank or ins company will accept their report. Then after that, I would start checking references. This is probably common sense to most folks but it wasn't to me which is the only reason I mention it.
I have heard a lot of good things about John Spencer.