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Probably not a huge difference in use I guess, and it does on how deep the belly of your knife is on how the angle differs along the blade.
A santoku won't change much, but a more western chef's knife will.
The top & belly are going to effectively have a finer angle - which probably works for finer cutting. Not sure I'd want it on a boning knife, say, as it would just lose the edge all the time.
Horl question - With knife sharpening, aren't you looking to achieve a consistent angle perpendicular to the edge, rather than parallel with the spine?