When I had my 400D/XTi, I found myself spending too much time second-guessing what the Canon evaluative metering mode is "thinking". Finally, I decide it's not worth my trouble and just use center-weight most of the time. Partial during some situation, and also adjust compensation when required. I learned photography using center-weight, so that's intuitive to me.
That's why there are all these metering modes. Different users, different scenarios.
Another thing is that the 400D's evaluative metering really wants to protect highlights. My theory is that they assume most users will shoot in JPEG and if they blow the highlights, they're gone. That's a valid point, but 1) straight out of the camera, many shots are underexposed; and 2) if you shoot RAW, you can pull back some of the blown highlights anyways.
Those are additional reasons why I didn't use evaluative metering with my 400D/XTi, and still don't with my 40D.
As for the Sunny 16 rule. Metering is valid, but most lenses are most sharp with least aberration at f8-11. f16 doesn't give one the best IQ.
As for that 185mm picture at 1/25, I hope there's no air movement at all and your tripod is sturdy enough for the 40D + 70-200/f4 combo. It's a dark scene and that shutter speed is very slow. You already maxed out the aperture, so you need to bump up your ISO. Moving from 100 to 400 will mean upping the shutter speed to 1/100.
You also mentioned you get better results with manual focus. That means autofocus is not doing its job. What mode are you in and which focus point? For a picture like that, you should be using one-shot mode and use only center point focus. Sometimes refocus will also help.