Just updating to share some further findings.
– Brier and others claim that the great pyramids were raided by tomb-raiders during the mid kingdom; yet in the early 19th century people apparantly had to use dynamite to get into the pyramid at all. I am not saying it is impossible to combine these two claims/observation into a meaningful explanation, but it is difficult. I haven’t found a good one myself yet – if anyone has, please share.
– It seems established in the mainstream that apart from graffiti from workers there are no inscriptions or markings of any kind inside or outside the pyramids. This would go against the practice of ancient Egyptians, who seemed to usually narrate the life of the pharaoh in his/her tomb in form of hieroglyphs (even going back all the way to Narmer). Regarding the graffiti I am quoting an opinion expressed on http://hallofthegods.org/articles/who-built-great-pyramid.html: “The most solid piece of evidence supporting the premise that the Great Pyramid, and by inference the other Giza monuments, originated in the 4th dynasty is the ‘workmen’s graffiti’. This graffiti was discovered by an English adventurer, Colonel Howard Vyse in 1837. It was found inside sealed chambers (the ‘relieving chambers’ above the King’s Chamber) and contained references to Khufu. Thus, on this basis, it was concluded that Khufu had indeed built the pyramid. The authenticity of the workmen’s graffiti in the Great Pyramid is questionable. Alsford and many other authors claim that the graffiti could have been faked. It was known at the time that Colonel Vyse had expended many years and a great deal of money on expeditions to Egypt, but had failed to unearth anything of major significance until his ‘amazing’ discovery in the Great Pyramid. The Graffiti could have easily been fabricated by copying inscriptions which had already been discovered on other structures and in the quarries nearby. Interestingly, the graffiti was only found in the chambers broken into by the Colonel. The so called Davidson chamber, lying below the other chambers and discovered by an earlier explorer, had no such graffiti. Indeed the rest of the pyramid is strangely devoid of markings of any kind. In the absence of any attempt to radiocarbon date the ‘red ochre’ paint which was used to daub the graffiti onto the massive granite blocks in the relieving chambers, debate as to the authenticity of the graffiti will continue.”