* metering linked to active AF-field in Spot metering?
Canon's iFCL color metering always factors in the active AF points. FOCUS, COLOR and LUMINANCE metering. Its weighted, and exactly what weighting it gets depends on your metering mode, but this has been around since the 7D was released (and is available in all other bodies that use iFCL metering, including the 5D III.)
I think you're missing the point. Those long statements from Canon about iFCL metering which you posted are referring to evaluative metering, and yes, that's been weighted toward the selected AF point for a long time. What AvTvM is talking about is spot metering, where the metering is done exclusively (not 'weighted' to some unknown fraction) at a small spot (1.5-4% of the field, depending on model). On 1-series bodies, that spot metering areas can be immediately surrounding any selected AF point, whereas on all other current bodies, spot metering is only in the center, regardles of the AF point seleted (meaning if you want an off-center subject and you want to focus and meter specifically on that subject, you must meter-AELock-recompose-focus-shoot, vs. just shoot).
Try it yourself on a non-1-series - put an off-center AF point on a static subject that's much darker or brighter than the rest of the scene, meter using evaluative metering, then try spot metering right on that subject - you'll usually get a different exposure value, sometimes very
different depending on subject and background.