The Sunny 16 f/11 exposure came closest to the actual scene with regards to exposure of the mid to high tones (grass and sky). Compare against the exposure against the CWM and MXM exposures and you will see CWM over-exposes by 1/3 stop and MXM by 2/3. Neither of these did well because of the high contrast, and MXM in particular was biased by the AF focus point on that palm trunk in the center, which, although under full sun, tends toward the dark tone range of the scale.

Test #2: Hill side under full sun

This next scene is not as contrasty as our previous one. Unfortunately, the photographer, dodo that he is, focused dead center, where a darker spot appears. Since MXM biases for the AF point, this choice led to over-exposure as well. This time we only show the Sunny 16 shot and the adjusted, f/11 shot for simplicity. Once again, we select f/11 as our baseline for comparison against metered results.

	Manual, ISO100, f/16, 1/100sec	Manual, ISO100, f/11, 1/100sec
Aperture Priority, CWM, ISO100, f/16, 1/30sec	Shutter Priority, CWM, ISO100, f/9, 1/100sec	Aperture Priority, MXM, ISO100, f/16, 1/20sec	Shutter Priority, MXM, ISO100, f/4, 1/100sec

Test #3: Flowers under full sun

Now I moved in closer to a group of flowers and repeated the same battery of tests. The focus point this time was one of the flowers on the left-bottom corner of the frame.

	Manual, ISO100, f/16, 1/100sec	Manual, ISO100, f/11, 1/100sec
Aperture Priority, CWM, ISO100, f/16, 1/50sec(*)	Shutter Priority, CWM, ISO100, f/11, 1/100sec(*)	Aperture Priority, MXM, ISO100, f/16, 1/40sec	Shutter Priority, MXM, ISO100, f/10, 1/100sec

At last, the CWM exposure agrees with adjusted Sunny 16 (Sunny 11) exposure, and MXM didn't do too bad, over-exposing by 1/3 stop.

Test #4: Cacti under full sun

Next I selected a scene with a range of green tones, still under full sun, but perhaps a bit more challenging in terms of contrast. And this is a prickly subject, so what better subject could I select? Note that for this case, I adjusted the Sunny 16 exposure with shutter speed (to maintain DOF), and selected an adjusted exposure at 1/80 (+1/3EV) rather than the usual f11 (+1EV).

Manual, ISO100, f/16, 1/100sec	Manual, ISO100, f/16, 1/80sec	Manual, ISO100, f/11, 1/100sec
Aperture Priority, CWM, ISO100, f/16, 1/80sec(*)	Shutter Priority, CWM, ISO100, f/14, 1/100sec(*)	Aperture Priority, MXM, ISO100, f/16, 1/50sec	Shutter Priority, MXM, ISO100, f/11, 1/100sec

Once more CWM agrees with my assessment, but MXM falls +2/3 stops away.

Test #5: Socks full sun

For this next more evenly lit scene, results were very close. Here I didn't take the full battery of shots, just enough to show the closeness of the results. This is the type of situation where CWM and MXM do equally well. Then it's up to me (us) to adjust to get the exposure we want either in camera or with PP.

Manual, ISO100, f/16, 1/100sec

Manual, ISO100, f/14, 1/100sec

Aperture Priority, CWM, ISO100, f/16, 1/160sec

Aperture Priority, MXM, ISO100, f/16, 1/100sec

Parting thoughts

Some inconclusive musings before we leave this subject:

1. Sunny 16 is just a guide, and with the D80 it seems more appropriate to start off with Sunny 11, then adjust as needed. This will be specially useful when using AI-S lenses which disable metering in your D80 or like camera.
2. Matrix Metering biases toward the AF focus point (see also this write-up for more details), as demonstrated by tests 1 and 2. In a way it behaves like spot metering on steroids, so use this fact wisely. Namely, avoid focusing on dark spots when using MXM unless you want over-exposure. If your subject is darker than the rest of the scene, adjust or select another exposure evaluation method.
3. As a general rule of thumb, I now select Center-weighed metering when the scene has lots of contrast, and elect Matrix Metering for scenes that are more evenly lit or when shooting with flash indoors.

Take away lesson: know your tools and select the right one for the job. Just like you wouldn't cut wood with a drill or drill holes with a circular saw, don't expect that MXM or CWM will "cut it" or "drill it" in every situation.