I am curious that you are all so specific about settings.
All recommendations regardless of how specific are starting points. Every scene situation is different.
I just set my flash on matrix DTTL and leave the flash head to zoom if I have a zoom lens fitted.
The issue with the 3D multi-sensor Balanced fill flash DTTL is that it has a brain of its own. It does everything for you. This is fine if it works. The problem is that if it doesn't work and you make your own adjustments, it still doesn't stop thinking. It may actually compensate for your compensation and you have no idea what it has done. It doesn't tell you.
Camera on matrix metering and whether I shot on M or A at pretty much whatever aperture I chose DTTL worked just great. For both fill flash for balanced light or for flash only macro.
If it works, then great. It doesn't matter what the camera's meter is set to if you are using flash as a primary source of light. It's how the flash measures the scene that determines when the flash will be quenched. The spot metering recommendation is a way to peg the exposure of an area outside the flash's range. Example: when shooting a blue water background with camera in manual, point the camera at the area of blue water you want exposed to the equivalent of 18% gray. Set exposure to properly expose this spot. Higher/shallower water will be lighter and lower/deeper water will be darker. Now when you start moving your camera around adjusting the composition, your exposure settings remains the same. If shooting A, you must hit the AE lock or the exposure changes when you point the camera at the subject.
If you are matrix metering, a super secret proprietary passle of locations are being evaluated to determine the best exposure for the entire scene. In 3D multi sensor balanced fill flash, it will figure out everything for you. It will actually take into consideration the distance and figure out all the proper exposures. It may adjust your ambient exposure and compensate the flash. You never know. Like I said, if it works, it works. If it doesn't, you won't know how to adjust it.
In standard D-TTL in either M or aperture with flash set on slow sync (without slow synch the camera defaults to 1/60), you can meter the scene with any technique you want, either spot meter or matrix. In standard D-TTL and doing fill flash, the tendency will be to overexpose the nearest thing to the flash because it is including darker background in its calculation that is outside the range of the strobe. Hence, the recommendation to reduce the flash exposure.
Now, only slightly off subject, there seems to be some undercurrent swirling about that using TTL is some sort of crutch or tool used by the incompetent photographers. Nothing could be further from the truth. I will debunk the "manual is better" myth in my 2nd article as soon as I finish my 1st article.
James, I'm familiar with "TTB" strobe control that you well know about. A common acquaintance of ours repeated the "TTB" theme to me almost in a preachy tone. But with a wry smile, he went out and shot wide angle in TTL with a -1 EV.