The Funicular concept is an attempt to explain how they moved all that stone from the Nile up to the Pyramid site. To date, it is the best answer, as all the Pyramids and their respective Causeways are at a 4.6 degree angle. You can prove this to yourself by using Google earth, measuring the height both end, and the length. Then plot that angle and length using a CAD program and/or Sketchup. The AE's religion changed over 100's of years, though not that angle.
Some of the boat pits are square in front while others are helm shaped. Why is that? Now the Funicular concept is a relatively easy concept to grasp. They understood what a counterbalance scale is, as many walls have painted pictures of them. A Funicular system is a counterbalance scale on it's side. Now I could be completely wrong in every regard, though if they used it, moving stones up a grade would have been allot easier than attempting logs, or pouring water over sand. At this point, it seems to come down to how intelligent or stupid you believe the AE were. Why did all the Pyramids, which unitized stone in their construction, feel the need for a Causeway. Two outer platforms with a lower center section. Even if you don't like the Funicular counterbalance system, pulling a sled up hill with men on both platforms with ropes, makes more sense, than over land.
In contrast, a canal cuts across a drainage divide atop a ridge (however humble), generally requiring an external water source above the highest elevation.
There are two broad types of canal:
Waterways: canals and navigations used for carrying vessels transporting goods and people. These can be subdivided into two kinds:
Those connecting existing lakes, rivers, other canals or seas and oceans.
Those connected in a city network: such as the Canal Grande and others of Venice Italy; the gracht of Amsterdam, and the waterways of Bangkok.
Aqueducts: water supply canals that are used for the conveyance and delivery of potable water for human consumption, municipal uses, hydro power canals and agriculture irrigation.
There is no size requirements, which differentiates a Canal from a Trench.
Obviously, a Giza Canal would not be for transporting vessels, unless you consider the inner section between the Pyramid and Walls a Canal. Though I have seen sizable canals/trenches for the conveyance of water up on the Giza Plateau. Additionally, once a canal is no longer needed, it can be filed in with stone. Would anyone be able to tell the difference. The trench along side Khafre's Causeway, as I understand it, stops mid way up. This trench drains into the Sphinx. Where did that water originate?
If not a Causeway, how did the AE move stone up and over the walls of a deep quarry. They are surrounded by high walls and the Causeway. If it were me, I would enter that Causeway down hill, ASAP.