So, my effect for the icon mouseover for my dock is magnify, but when I do this on a subdock (which I have displaying on mouseover), it first magnifies, then shrinks back to regular size before displaying the subdock. So essentially it doesn't flow well and is somewhat jarring. I'm wondering whether you might consider adding a way for subdocks to display without the container icon they are in having to de-magnify first.
My other suggestion around this would be to allow for a separate effect for the subdock icons, as well as some other settings that currently you can only do via your main dock - like icon size. So maybe since you wouldn't have the same constraints as you do with lots of icons on your main dock, you could sepecify a large icon size for a subdock that only has 4 items in it, and so they would ALREADY be "magnified" without having to do the mouseover to get that magnification, if that makes any sense.
Something for the next version, at least, right?

Levi