Adjusting Hozan spoke threading tool for different spoke gauges
I have inadvertently threaded many spokes with my Hozan not properly centered vertically -- so much that the threaded ends were bent slightly. They laced up fine in the wheels. Of course I corrected this after I noticed, but I'd say the difference I got due to my error was much more than the fraction of a mm difference you'd get in height by moving between those spoke sizes. 

The vertical centering is so imprecise, were I to move to another size, and if I had mine nicely centered already, I wouldn't bother trying to recenter, because I think I'd be equally likely to make it worse.

But I second the notion of threading a spare(s) of different sizes to see if you even notice a difference.