Whoever said they could “measure” with an MT6 did not know what they were taking about. It is not accurate enough to measure the length of a nail. It does “beep” when slid across a truss for several feet(when it is not near other metal objects), if you mark the beeps it will give you an accurate “representation” of nail spacing. It will not tell you exactly where the nails are or their size.
Actually ignorance and assumptions are the biggest issue with MOST insurance inspections. The second is the unprofessional-ism of the inspectors who think they are smarter than all the engineers and all the others in the insurance industry.
BTW, if it is dangerous to crawl an attic you should not do it. Safety first. We have done more than 20k inspections and not much more than a splinter so far.