We had a few pages exploring this in detail, until the complaints came in (and I took down my post on what I'm about to say

).
Based on the 1500+ pages of design documents I've reviewed on the 4430/4460 (to find the relevant few dozen or less) - it's simply better to indicate that both the 4430 and 4460 are
clocked. Overclocking and underclocking here may not really translate to the way you may think of other processors and binning.
While the original spec targets were 1 and 1.5 GHz respectively, and the face on the web reflects that, there's really quite a bit more to it with the OMAP4 family.
I have yet to find a single public reference to support the idea that the 4430 and 4460 are made on the same wafers. Would love to see something that backs that up because it's still unreasonable to me - not impossible - just unreasonable.